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lammps/doc/html/fix_adapt.html
2025-01-13 14:55:48 +00:00

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<title>fix adapt command &mdash; LAMMPS documentation</title>
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<div class="lammps_version">Version: <b>19 Nov 2024</b></div>
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<li class="toctree-l1"><a class="reference internal" href="Intro.html">1. Introduction</a></li>
<li class="toctree-l1"><a class="reference internal" href="Install.html">2. Install LAMMPS</a></li>
<li class="toctree-l1"><a class="reference internal" href="Build.html">3. Build LAMMPS</a></li>
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<p class="caption" role="heading"><span class="caption-text">Programmer Guide</span></p>
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<li class="toctree-l1"><a class="reference internal" href="Library.html">1. LAMMPS Library Interfaces</a></li>
<li class="toctree-l1"><a class="reference internal" href="Python_head.html">2. Use Python with LAMMPS</a></li>
<li class="toctree-l1"><a class="reference internal" href="Modify.html">3. Modifying &amp; extending LAMMPS</a></li>
<li class="toctree-l1"><a class="reference internal" href="Developer.html">4. Information for Developers</a></li>
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<p class="caption" role="heading"><span class="caption-text">Command Reference</span></p>
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<li class="toctree-l1"><a class="reference internal" href="commands_list.html">Commands</a></li>
<li class="toctree-l1 current"><a class="reference internal" href="fixes.html">Fix Styles</a><ul class="current">
<li class="toctree-l2"><a class="reference internal" href="fix_accelerate_cos.html">fix accelerate/cos command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_acks2_reaxff.html">fix acks2/reaxff command</a></li>
<li class="toctree-l2 current"><a class="current reference internal" href="#">fix adapt command</a><ul>
<li class="toctree-l3"><a class="reference internal" href="#syntax">Syntax</a></li>
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<li class="toctree-l3"><a class="reference internal" href="#description">Description</a></li>
<li class="toctree-l3"><a class="reference internal" href="#restart-fix-modify-output-run-start-stop-minimize-info">Restart, fix_modify, output, run start/stop, minimize info</a></li>
<li class="toctree-l3"><a class="reference internal" href="#restrictions">Restrictions</a></li>
<li class="toctree-l3"><a class="reference internal" href="#related-commands">Related commands</a></li>
<li class="toctree-l3"><a class="reference internal" href="#default">Default</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_adapt_fep.html">fix adapt/fep command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_add_heat.html">fix add/heat command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_addforce.html">fix addforce command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_addtorque.html">fix addtorque command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_alchemy.html">fix alchemy command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_amoeba_bitorsion.html">fix amoeba/bitorsion command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_amoeba_pitorsion.html">fix amoeba/pitorsion command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_append_atoms.html">fix append/atoms command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_atc.html">fix atc command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_atom_swap.html">fix atom/swap command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_ave_atom.html">fix ave/atom command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_ave_chunk.html">fix ave/chunk command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_ave_correlate.html">fix ave/correlate command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_ave_correlate_long.html">fix ave/correlate/long command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_ave_grid.html">fix ave/grid command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_ave_histo.html">fix ave/histo command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_ave_histo.html#fix-ave-histo-weight-command">fix ave/histo/weight command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_ave_spatial.html">fix ave/spatial command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_ave_spatial_sphere.html">fix ave/spatial/sphere command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_ave_time.html">fix ave/time command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_aveforce.html">fix aveforce command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_balance.html">fix balance command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_bocs.html">fix bocs command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_bond_break.html">fix bond/break command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_bond_create.html">fix bond/create command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_bond_create.html#fix-bond-create-angle-command">fix bond/create/angle command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_bond_react.html">fix bond/react command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_bond_swap.html">fix bond/swap command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_box_relax.html">fix box/relax command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_brownian.html">fix brownian command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_brownian.html#fix-brownian-sphere-command">fix brownian/sphere command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_brownian.html#fix-brownian-asphere-command">fix brownian/asphere command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_charge_regulation.html">fix charge/regulation command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_cmap.html">fix cmap command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_colvars.html">fix colvars command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_controller.html">fix controller command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_damping_cundall.html">fix damping/cundall command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_deform.html">fix deform command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_deform_pressure.html">fix deform/pressure command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_deposit.html">fix deposit command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_dpd_energy.html">fix dpd/energy command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_dpd_source.html">fix edpd/source command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_dpd_source.html#fix-tdpd-source-command">fix tdpd/source command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_drag.html">fix drag command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_drude.html">fix drude command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_drude_transform.html">fix drude/transform/direct command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_drude_transform.html#fix-drude-transform-inverse-command">fix drude/transform/inverse command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_dt_reset.html">fix dt/reset command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_efield.html">fix efield command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_efield.html#fix-efield-tip4p-command">fix efield/tip4p command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_ehex.html">fix ehex command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_electrode.html">fix electrode/conp command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_electrode.html#fix-electrode-conq-command">fix electrode/conq command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_electrode.html#fix-electrode-thermo-command">fix electrode/thermo command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_electron_stopping.html">fix electron/stopping command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_electron_stopping.html#fix-electron-stopping-fit-command">fix electron/stopping/fit command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_enforce2d.html">fix enforce2d command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_eos_cv.html">fix eos/cv command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_eos_table.html">fix eos/table command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_eos_table_rx.html">fix eos/table/rx command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_evaporate.html">fix evaporate command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_external.html">fix external command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_ffl.html">fix ffl command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_filter_corotate.html">fix filter/corotate command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_flow_gauss.html">fix flow/gauss command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_freeze.html">fix freeze command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_gcmc.html">fix gcmc command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_gld.html">fix gld command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_gle.html">fix gle command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_gravity.html">fix gravity command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_grem.html">fix grem command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_halt.html">fix halt command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_heat.html">fix heat command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_heat_flow.html">fix heat/flow command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_hyper_global.html">fix hyper/global command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_hyper_local.html">fix hyper/local command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_imd.html">fix imd command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_indent.html">fix indent command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_ipi.html">fix ipi command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_langevin.html">fix langevin command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_langevin_drude.html">fix langevin/drude command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_langevin_eff.html">fix langevin/eff command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_langevin_spin.html">fix langevin/spin command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_lb_fluid.html">fix lb/fluid command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_lb_momentum.html">fix lb/momentum command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_lb_viscous.html">fix lb/viscous command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_lineforce.html">fix lineforce command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_manifoldforce.html">fix manifoldforce command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_mdi_qm.html">fix mdi/qm command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_mdi_qmmm.html">fix mdi/qmmm command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_meso_move.html">fix meso/move command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_mol_swap.html">fix mol/swap command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_momentum.html">fix momentum command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_momentum.html#fix-momentum-chunk-command">fix momentum/chunk command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_move.html">fix move command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_msst.html">fix msst command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_mvv_dpd.html">fix mvv/dpd command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_mvv_dpd.html#fix-mvv-edpd-command">fix mvv/edpd command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_mvv_dpd.html#fix-mvv-tdpd-command">fix mvv/tdpd command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_neb.html">fix neb command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_neb_spin.html">fix neb/spin command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nh.html">fix nvt command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nh.html#fix-npt-command">fix npt command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nh.html#fix-nph-command">fix nph command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nh_eff.html">fix nvt/eff command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nh_eff.html#fix-npt-eff-command">fix npt/eff command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nh_eff.html#fix-nph-eff-command">fix nph/eff command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nh_uef.html">fix nvt/uef command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nh_uef.html#fix-npt-uef-command">fix npt/uef command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nonaffine_displacement.html">fix nonaffine/displacement command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nph_asphere.html">fix nph/asphere command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nph_body.html">fix nph/body command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nph_sphere.html">fix nph/sphere command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nphug.html">fix nphug command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_npt_asphere.html">fix npt/asphere command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_npt_body.html">fix npt/body command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_npt_cauchy.html">fix npt/cauchy command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_npt_sphere.html">fix npt/sphere command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_numdiff.html">fix numdiff command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_numdiff_virial.html">fix numdiff/virial command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nve.html">fix nve command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nve_asphere.html">fix nve/asphere command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nve_asphere_noforce.html">fix nve/asphere/noforce command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nve_awpmd.html">fix nve/awpmd command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nve_body.html">fix nve/body command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nve_bpm_sphere.html">fix nve/bpm/sphere command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nve_dot.html">fix nve/dot command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nve_dotc_langevin.html">fix nve/dotc/langevin command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nve_eff.html">fix nve/eff command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nve_limit.html">fix nve/limit command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nve_line.html">fix nve/line command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nve_manifold_rattle.html">fix nve/manifold/rattle command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nve_noforce.html">fix nve/noforce command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nve_sphere.html">fix nve/sphere command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nve_spin.html">fix nve/spin command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nve_tri.html">fix nve/tri command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nvk.html">fix nvk command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nvt_asphere.html">fix nvt/asphere command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nvt_body.html">fix nvt/body command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nvt_manifold_rattle.html">fix nvt/manifold/rattle command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nvt_sllod.html">fix nvt/sllod command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nvt_sllod_eff.html">fix nvt/sllod/eff command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_nvt_sphere.html">fix nvt/sphere command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_oneway.html">fix oneway command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_orient.html">fix orient/fcc command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_orient.html#fix-orient-bcc-command">fix orient/bcc command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_orient_eco.html">fix orient/eco command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_pafi.html">fix pafi command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_pair.html">fix pair command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_phonon.html">fix phonon command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_pimd.html">fix pimd/langevin command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_pimd.html#fix-pimd-nvt-command">fix pimd/nvt command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_pimdb.html">fix pimdb/langevin command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_plumed.html">fix plumed command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_poems.html">fix poems command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_polarize.html">fix polarize/bem/gmres command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_qbmsst.html">fix qbmsst command</a></li>
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<p><span class="math notranslate nohighlight">\(\renewcommand{\AA}{\text{Å}}\)</span></p>
<section id="fix-adapt-command">
<span id="index-0"></span><h1>fix adapt command<a class="headerlink" href="#fix-adapt-command" title="Link to this heading"></a></h1>
<section id="syntax">
<h2>Syntax<a class="headerlink" href="#syntax" title="Link to this heading"></a></h2>
<div class="highlight-LAMMPS notranslate"><div class="highlight"><pre><span></span><span class="k">fix </span><span class="nv nv-Identifier">ID</span><span class="w"> </span><span class="nv nv-Identifier">group-ID</span><span class="w"> </span><span class="n">adapt</span><span class="w"> </span><span class="n">N</span><span class="w"> </span><span class="n">attribute</span><span class="w"> </span><span class="n">args</span><span class="w"> </span><span class="n">...</span><span class="w"> </span><span class="n">keyword</span><span class="w"> </span><span class="n">value</span><span class="w"> </span><span class="n">...</span>
</pre></div>
</div>
<ul>
<li><p>ID, group-ID are documented in <a class="reference internal" href="fix.html"><span class="doc">fix</span></a> command</p></li>
<li><p>adapt = style name of this fix command</p></li>
<li><p>N = adapt simulation settings every this many timesteps</p></li>
<li><p>one or more attribute/arg pairs may be appended</p></li>
<li><p>attribute = <em>pair</em> or <em>bond</em> or <em>angle</em> or <em>kspace</em> or <em>atom</em></p>
<pre class="literal-block"><em>pair</em> args = pstyle pparam I J v_name
pstyle = pair style name (e.g., lj/cut)
pparam = parameter to adapt over time
I,J = type pair(s) to set parameter for (integer or type label)
v_name = variable with name that calculates value of pparam
<em>bond</em> args = bstyle bparam I v_name
bstyle = bond style name (e.g., harmonic)
bparam = parameter to adapt over time
I = type bond to set parameter for (integer or type label)
v_name = variable with name that calculates value of bparam
<em>angle</em> args = astyle aparam I v_name
astyle = angle style name (e.g., harmonic)
aparam = parameter to adapt over time
I = type angle to set parameter for (integer or type label)
v_name = variable with name that calculates value of aparam
<em>kspace</em> arg = v_name
v_name = variable with name that calculates scale factor on <span class="math notranslate nohighlight">\(k\)</span>-space terms
<em>atom</em> args = atomparam v_name
atomparam = <em>charge</em> or <em>diameter</em> or <em>diameter/disc</em> = parameter to adapt over time
v_name = variable with name that calculates value of atomparam</pre>
</li>
<li><p>zero or more keyword/value pairs may be appended</p></li>
<li><p>keyword = <em>scale</em> or <em>reset</em> or <em>mass</em></p>
<pre class="literal-block"><em>scale</em> value = <em>no</em> or <em>yes</em>
<em>no</em> = the variable value is the new setting
<em>yes</em> = the variable value multiplies the original setting
<em>reset</em> value = <em>no</em> or <em>yes</em>
<em>no</em> = values will remain altered at the end of a run
<em>yes</em> = reset altered values to their original values at the end of a run
<em>mass</em> value = <em>no</em> or <em>yes</em>
<em>no</em> = mass is not altered by changes in diameter
<em>yes</em> = mass is altered by changes in diameter</pre>
</li>
</ul>
</section>
<section id="examples">
<h2>Examples<a class="headerlink" href="#examples" title="Link to this heading"></a></h2>
<div class="highlight-LAMMPS notranslate"><div class="highlight"><pre><span></span><span class="k">fix </span><span class="nv nv-Identifier">1</span><span class="w"> </span><span class="nv nv-Identifier">all</span><span class="w"> </span><span class="n">adapt</span><span class="w"> </span><span class="m">1</span><span class="w"> </span><span class="n">pair</span><span class="w"> </span><span class="n">soft</span><span class="w"> </span><span class="n">a</span><span class="w"> </span><span class="m">1</span><span class="w"> </span><span class="m">1</span><span class="w"> </span><span class="n">v_prefactor</span>
<span class="k">fix </span><span class="nv nv-Identifier">1</span><span class="w"> </span><span class="nv nv-Identifier">all</span><span class="w"> </span><span class="n">adapt</span><span class="w"> </span><span class="m">1</span><span class="w"> </span><span class="n">pair</span><span class="w"> </span><span class="n">soft</span><span class="w"> </span><span class="n">a</span><span class="w"> </span><span class="m">2</span><span class="o">*</span><span class="w"> </span><span class="m">3</span><span class="w"> </span><span class="n">v_prefactor</span>
<span class="k">fix </span><span class="nv nv-Identifier">1</span><span class="w"> </span><span class="nv nv-Identifier">all</span><span class="w"> </span><span class="n">adapt</span><span class="w"> </span><span class="m">1</span><span class="w"> </span><span class="n">pair</span><span class="w"> </span><span class="n">lj</span><span class="o">/</span><span class="n">cut</span><span class="w"> </span><span class="n">epsilon</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="n">v_scale1</span><span class="w"> </span><span class="n">pair</span><span class="w"> </span><span class="n">coul</span><span class="o">/</span><span class="n">cut</span><span class="w"> </span><span class="n">scale</span><span class="w"> </span><span class="m">3</span><span class="w"> </span><span class="m">3</span><span class="w"> </span><span class="n">v_scale2</span><span class="w"> </span><span class="n">scale</span><span class="w"> </span><span class="n">yes</span><span class="w"> </span><span class="n">reset</span><span class="w"> </span><span class="n">yes</span>
<span class="k">fix </span><span class="nv nv-Identifier">1</span><span class="w"> </span><span class="nv nv-Identifier">all</span><span class="w"> </span><span class="n">adapt</span><span class="w"> </span><span class="m">10</span><span class="w"> </span><span class="n">atom</span><span class="w"> </span><span class="n">diameter</span><span class="w"> </span><span class="n">v_size</span>
<span class="k">variable </span><span class="nv nv-Identifier">ramp_up</span><span class="w"> </span><span class="n">equal</span><span class="w"> </span><span class="s">&quot;ramp(0.01,0.5)&quot;</span>
<span class="k">fix </span><span class="nv nv-Identifier">stretch</span><span class="w"> </span><span class="nv nv-Identifier">all</span><span class="w"> </span><span class="n">adapt</span><span class="w"> </span><span class="m">1</span><span class="w"> </span><span class="n">bond</span><span class="w"> </span><span class="n">harmonic</span><span class="w"> </span><span class="n">r0</span><span class="w"> </span><span class="m">1</span><span class="w"> </span><span class="n">v_ramp_up</span>
<span class="k">labelmap</span><span class="w"> </span><span class="n">atom</span><span class="w"> </span><span class="m">1</span><span class="w"> </span><span class="n">c1</span>
<span class="k">fix </span><span class="nv nv-Identifier">1</span><span class="w"> </span><span class="nv nv-Identifier">all</span><span class="w"> </span><span class="n">adapt</span><span class="w"> </span><span class="m">1</span><span class="w"> </span><span class="n">pair</span><span class="w"> </span><span class="n">soft</span><span class="w"> </span><span class="n">a</span><span class="w"> </span><span class="n">c1</span><span class="w"> </span><span class="n">c1</span><span class="w"> </span><span class="n">v_prefactor</span>
</pre></div>
</div>
</section>
<section id="description">
<h2>Description<a class="headerlink" href="#description" title="Link to this heading"></a></h2>
<p>Change or adapt one or more specific simulation attributes or settings over
time as a simulation runs. Pair potential and <span class="math notranslate nohighlight">\(k\)</span>-space and atom
attributes which can be varied by this fix are discussed below. Many other
fixes can also be used to time-vary simulation parameters (e.g., the
<a class="reference internal" href="fix_deform.html"><span class="doc">fix deform</span></a> command will change the simulation box
size/shape and the <a class="reference internal" href="fix_move.html"><span class="doc">fix move</span></a> command will change atom
positions and velocities in a prescribed manner). Also note that many commands
allow variables as arguments for specific parameters, if described in that
manner on their doc pages. An equal-style variable can calculate a
time-dependent quantity, so this is another way to vary a simulation parameter
over time.</p>
<p>If <span class="math notranslate nohighlight">\(N\)</span> is specified as 0, the specified attributes are only changed
once, before the simulation begins. This is all that is needed if the
associated variables are not time-dependent. If <span class="math notranslate nohighlight">\(N &gt; 0\)</span>, then changes
are made every <span class="math notranslate nohighlight">\(N\)</span> steps during the simulation, presumably with a
variable that is time-dependent.</p>
<p>Depending on the value of the <em>reset</em> keyword, attributes changed by
this fix will or will not be reset back to their original values at
the end of a simulation. Even if <em>reset</em> is specified as <em>yes</em>, a
restart file written during a simulation will contain the modified
settings.</p>
<p>If the <em>scale</em> keyword is set to <em>no</em>, which is the default, then
the value of the altered parameter will be whatever the variable
generates. If the <em>scale</em> keyword is set to <em>yes</em>, then the value
of the altered parameter will be the initial value of that parameter
multiplied by whatever the variable generates (i.e., the variable is
now a “scale factor” applied in (presumably) a time-varying fashion to
the parameter).</p>
<p>Note that whether scale is <em>no</em> or <em>yes</em>, internally, the parameters
themselves are actually altered by this fix. Make sure you use the
<em>reset yes</em> option if you want the parameters to be restored to their
initial values after the run.</p>
<hr class="docutils" />
<p>The <em>pair</em> keyword enables various parameters of potentials defined by
the <a class="reference internal" href="pair_style.html"><span class="doc">pair_style</span></a> command to be changed, if the pair
style supports it. Note that the <a class="reference internal" href="pair_style.html"><span class="doc">pair_style</span></a> and
<a class="reference internal" href="pair_coeff.html"><span class="doc">pair_coeff</span></a> commands must be used in the usual manner
to specify these parameters initially; the fix adapt command simply
overrides the parameters.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>Pair_coeff settings must be made <strong>explicitly</strong> in order for fix
adapt to be able to change them. Settings inferred from mixing
are not suitable. If necessary all mixed settings can be output
to a file using the <a class="reference internal" href="write_coeff.html"><span class="doc">write_coeff command</span></a> and
then the desired mixed pair_coeff settings copied from that file.</p>
</div>
<p>The <em>pstyle</em> argument is the name of the pair style. If
<a class="reference internal" href="pair_hybrid.html"><span class="doc">pair_style hybrid or hybrid/overlay</span></a> is used,
<em>pstyle</em> should be a sub-style name. If there are multiple
sub-styles using the same pair style, then <em>pstyle</em> should be specified
as “style:N”, where <em>N</em> is which instance of the pair style you wish to
adapt (e.g., the first or second). For example, <em>pstyle</em> could be
specified as “soft” or “lubricate” or “lj/cut:1” or “lj/cut:2”. The
<em>pparam</em> argument is the name of the parameter to change. This is the
current list of pair styles and parameters that can be varied by this
fix. See the doc pages for individual pair styles and their energy
formulas for the meaning of these parameters:</p>
<table class="docutils align-default">
<tbody>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_born.html"><span class="doc">born</span></a></p></td>
<td><p>a,b,c</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_born.html"><span class="doc">born/coul/long, born/coul/msm</span></a></p></td>
<td><p>coulombic_cutoff</p></td>
<td><p>type global</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_born_gauss.html"><span class="doc">born/gauss</span></a></p></td>
<td><p>biga0,biga1,r0</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_buck.html"><span class="doc">buck, buck/coul/cut</span></a></p></td>
<td><p>a,c</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_buck.html"><span class="doc">buck/coul/long, buck/coul/msm</span></a></p></td>
<td><p>a,c,coulombic_cutoff</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_mdf.html"><span class="doc">buck/mdf</span></a></p></td>
<td><p>a,c</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_coul.html"><span class="doc">coul/cut, coul/cut/global</span></a></p></td>
<td><p>scale</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_fep_soft.html"><span class="doc">coul/cut/soft</span></a></p></td>
<td><p>lambda</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_coul.html"><span class="doc">coul/debye</span></a></p></td>
<td><p>scale</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_coul.html"><span class="doc">coul/dsf</span></a></p></td>
<td><p>coulombic_cutoff</p></td>
<td><p>type global</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_coul.html"><span class="doc">coul/long, coul/msm</span></a></p></td>
<td><p>coulombic_cutoff, scale</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_fep_soft.html"><span class="doc">coul/long/soft</span></a></p></td>
<td><p>scale, lambda, coulombic_cutoff</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_coul_slater.html"><span class="doc">coul/slater/long</span></a></p></td>
<td><p>scale</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_coul.html"><span class="doc">coul/streitz</span></a></p></td>
<td><p>scale</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_eam.html"><span class="doc">eam, eam/alloy, eam/fs</span></a></p></td>
<td><p>scale</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_gauss.html"><span class="doc">gauss</span></a></p></td>
<td><p>a</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_harmonic_cut.html"><span class="doc">harmonic/cut</span></a></p></td>
<td><p>k, cutoff</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_kim.html"><span class="doc">kim</span></a></p></td>
<td><p>scale</p></td>
<td><p>type global</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_mdf.html"><span class="doc">lennard/mdf</span></a></p></td>
<td><p>A,B</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_class2.html"><span class="doc">lj/class2</span></a></p></td>
<td><p>epsilon,sigma</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_class2.html"><span class="doc">lj/class2/coul/cut, lj/class2/coul/long</span></a></p></td>
<td><p>epsilon,sigma,coulombic_cutoff</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_lj.html"><span class="doc">lj/cut</span></a></p></td>
<td><p>epsilon,sigma</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_lj_cut_coul.html"><span class="doc">lj/cut/coul/cut, lj/cut/coul/long, lj/cut/coul/msm</span></a></p></td>
<td><p>epsilon,sigma,coulombic_cutoff</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_fep_soft.html"><span class="doc">lj/cut/coul/cut/soft, lj/cut/coul/long/soft</span></a></p></td>
<td><p>epsilon,sigma,lambda,coulombic_cutoff</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_lj_cut_coul.html"><span class="doc">lj/cut/coul/dsf</span></a></p></td>
<td><p>cutoff</p></td>
<td><p>type global</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_lj_cut_tip4p.html"><span class="doc">lj/cut/tip4p/cut</span></a></p></td>
<td><p>epsilon,sigma,coulombic_cutoff</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_fep_soft.html"><span class="doc">lj/cut/soft</span></a></p></td>
<td><p>epsilon,sigma,lambda</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_lj_expand.html"><span class="doc">lj/expand</span></a></p></td>
<td><p>epsilon,sigma,delta</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_mdf.html"><span class="doc">lj/mdf</span></a></p></td>
<td><p>epsilon,sigma</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_dipole.html"><span class="doc">lj/sf/dipole/sf</span></a></p></td>
<td><p>epsilon,sigma,scale</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_lubricate.html"><span class="doc">lubricate</span></a></p></td>
<td><p>mu</p></td>
<td><p>global</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_meam.html"><span class="doc">meam</span></a></p></td>
<td><p>scale</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_mie.html"><span class="doc">mie/cut</span></a></p></td>
<td><p>epsilon,sigma,gamma_repulsive,gamma_attractive</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_morse.html"><span class="doc">morse, morse/smooth/linear</span></a></p></td>
<td><p>D0,R0,alpha</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_morse.html"><span class="doc">morse/soft</span></a></p></td>
<td><p>D0,R0,alpha,lambda</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_nm.html"><span class="doc">nm/cut</span></a></p></td>
<td><p>E0,R0,m,n</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_nm.html"><span class="doc">nm/cut/coul/cut, nm/cut/coul/long</span></a></p></td>
<td><p>E0,R0,m,n,coulombic_cutoff</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_pace.html"><span class="doc">pace, pace/extrapolation</span></a></p></td>
<td><p>scale</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_quip.html"><span class="doc">quip</span></a></p></td>
<td><p>scale</p></td>
<td><p>type global</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_snap.html"><span class="doc">snap</span></a></p></td>
<td><p>scale</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_spin_dmi.html"><span class="doc">spin/dmi</span></a></p></td>
<td><p>coulombic_cutoff</p></td>
<td><p>type global</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_spin_exchange.html"><span class="doc">spin/exchange</span></a></p></td>
<td><p>coulombic_cutoff</p></td>
<td><p>type global</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_spin_magelec.html"><span class="doc">spin/magelec</span></a></p></td>
<td><p>coulombic_cutoff</p></td>
<td><p>type global</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_spin_neel.html"><span class="doc">spin/neel</span></a></p></td>
<td><p>coulombic_cutoff</p></td>
<td><p>type global</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_soft.html"><span class="doc">soft</span></a></p></td>
<td><p>a</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_table.html"><span class="doc">table</span></a></p></td>
<td><p>table_cutoff</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="pair_ufm.html"><span class="doc">ufm</span></a></p></td>
<td><p>epsilon,sigma,scale</p></td>
<td><p>type pairs</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="pair_wf_cut.html"><span class="doc">wf/cut</span></a></p></td>
<td><p>epsilon,sigma,nu,mu</p></td>
<td><p>type pairs</p></td>
</tr>
</tbody>
</table>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>It is easy to add new pairwise potentials and their parameters
to this list. All it typically takes is adding an extract() method to
the pair_*.cpp file associated with the potential.</p>
</div>
<p>Some parameters are global settings for the pair style (e.g., the
viscosity setting “mu” for <a class="reference internal" href="pair_lubricate.html"><span class="doc">pair_style lubricate</span></a>).
Other parameters apply to atom type pairs within the pair style (e.g., the
prefactor <span class="math notranslate nohighlight">\(a\)</span> for <a class="reference internal" href="pair_soft.html"><span class="doc">pair_style soft</span></a>).</p>
<p>Note that for many of the potentials, the parameter that can be varied
is effectively a prefactor on the entire energy expression for the
potential (e.g., the lj/cut epsilon). The parameters listed as “scale”
are exactly that, since the energy expression for the
<a class="reference internal" href="pair_coul.html"><span class="doc">coul/cut</span></a> potential (for example) has no labeled
prefactor in its formula. To apply an effective prefactor to some
potentials, multiple parameters need to be altered. For example, the
<a class="reference internal" href="pair_buck.html"><span class="doc">Buckingham potential</span></a> needs both the <span class="math notranslate nohighlight">\(A\)</span> and
<span class="math notranslate nohighlight">\(C\)</span> terms altered together. To scale the Buckingham potential, you
should thus list the pair style twice, once for <span class="math notranslate nohighlight">\(A\)</span> and once for
<span class="math notranslate nohighlight">\(C\)</span>.</p>
<p>If a type pair parameter is specified, the <span class="math notranslate nohighlight">\(I\)</span> and <span class="math notranslate nohighlight">\(J\)</span> settings
should be specified to indicate which type pairs to apply it to. If a global
parameter is specified, the <span class="math notranslate nohighlight">\(I\)</span> and <span class="math notranslate nohighlight">\(J\)</span> settings still need to be
specified, but are ignored.</p>
<p>Similar to the <a class="reference internal" href="pair_coeff.html"><span class="doc">pair_coeff command</span></a>, <span class="math notranslate nohighlight">\(I\)</span> and
<span class="math notranslate nohighlight">\(J\)</span> can be specified in one of several ways. Explicit numeric values
can be used for each, as in the first example above. Or, one or both of
the types in the I,J pair can be a <a class="reference internal" href="Howto_type_labels.html"><span class="doc">type label</span></a>.
LAMMPS sets the coefficients for the symmetric <span class="math notranslate nohighlight">\(J,I\)</span> interaction to
the same values.</p>
<p>A wild-card asterisk can be used in place of or in conjunction with
the <span class="math notranslate nohighlight">\(I,J\)</span> arguments to set the coefficients for multiple pairs of atom
types. This takes the form “*” or “*n” or “m*” or “m*n”. If <span class="math notranslate nohighlight">\(N\)</span>
is the number of atom types, then an asterisk with no numeric values
means all types from 1 to <span class="math notranslate nohighlight">\(N\)</span>. A leading asterisk means all types from
1 to n (inclusive). A trailing asterisk means all types from m to <span class="math notranslate nohighlight">\(N\)</span>
(inclusive). A middle asterisk means all types from m to n
(inclusive). For the asterisk syntax, note that only type pairs with
<span class="math notranslate nohighlight">\(I \le J\)</span> are considered; if asterisks imply type pairs where
<span class="math notranslate nohighlight">\(J &lt; I\)</span>, they are ignored.</p>
<p>IMPORTANT NOTE: If <a class="reference internal" href="pair_hybrid.html"><span class="doc">pair_style hybrid or hybrid/overlay</span></a> is being used, then the <em>pstyle</em> will be a sub-style
name. You must specify <span class="math notranslate nohighlight">\(I,J\)</span> arguments that correspond to type pair
values defined (via the <a class="reference internal" href="pair_coeff.html"><span class="doc">pair_coeff</span></a> command) for
that sub-style.</p>
<p>The <em>v_name</em> argument for keyword <em>pair</em> is the name of an
<a class="reference internal" href="variable.html"><span class="doc">equal-style variable</span></a> which will be evaluated each time
this fix is invoked to set the parameter to a new value. It should be
specified as v_name, where name is the variable name. Equal-style
variables can specify formulas with various mathematical functions, and
include <a class="reference internal" href="thermo_style.html"><span class="doc">thermo_style</span></a> command keywords for the
simulation box parameters and timestep and elapsed time. Thus it is
easy to specify parameters that change as a function of time or span
consecutive runs in a continuous fashion. For the latter, see the
<em>start</em> and <em>stop</em> keywords of the <a class="reference internal" href="run.html"><span class="doc">run</span></a> command and the
<em>elaplong</em> keyword of <a class="reference internal" href="thermo_style.html"><span class="doc">thermo_style custom</span></a> for
details.</p>
<p>For example, these commands would change the prefactor coefficient of
the <a class="reference internal" href="pair_soft.html"><span class="doc">pair_style soft</span></a> potential from 10.0 to 30.0 in a
linear fashion over the course of a simulation:</p>
<div class="highlight-LAMMPS notranslate"><div class="highlight"><pre><span></span><span class="k">variable </span><span class="nv nv-Identifier">prefactor</span><span class="w"> </span><span class="n">equal</span><span class="w"> </span><span class="n">ramp</span><span class="nv">(10,30)</span>
<span class="k">fix </span><span class="nv nv-Identifier">1</span><span class="w"> </span><span class="nv nv-Identifier">all</span><span class="w"> </span><span class="n">adapt</span><span class="w"> </span><span class="m">1</span><span class="w"> </span><span class="n">pair</span><span class="w"> </span><span class="n">soft</span><span class="w"> </span><span class="n">a</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="n">v_prefactor</span>
</pre></div>
</div>
<hr class="docutils" />
<p>The <em>bond</em> keyword uses the specified variable to change the value of
a bond coefficient over time, very similar to how the <em>pair</em> keyword
operates. The only difference is that now a bond coefficient for a
given bond type is adapted.</p>
<p>A wild-card asterisk can be used in place of or in conjunction with the
bond type argument to set the coefficients for multiple bond types.
This takes the form “*” or “*n” or “m*” or “m*n”. If <span class="math notranslate nohighlight">\(N\)</span> is
the number of bond types, then an asterisk with no numeric values means
all types from 1 to <span class="math notranslate nohighlight">\(N\)</span>. A leading asterisk means all types from
1 to n (inclusive). A trailing asterisk means all types from m to
<span class="math notranslate nohighlight">\(N\)</span> (inclusive). A middle asterisk means all types from m to n
(inclusive).</p>
<p>If <a class="reference internal" href="bond_hybrid.html"><span class="doc">bond_style hybrid</span></a> is used, <em>bstyle</em> should be a
sub-style name. The bond styles that currently work with fix adapt are:</p>
<table class="docutils align-default">
<tbody>
<tr class="row-odd"><td><p><a class="reference internal" href="bond_class2.html"><span class="doc">class2</span></a></p></td>
<td><p>k2,k3,k4,r0</p></td>
<td><p>type bonds</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="bond_fene.html"><span class="doc">fene</span></a></p></td>
<td><p>k,r0</p></td>
<td><p>type bonds</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="bond_fene_expand.html"><span class="doc">fene/expand</span></a></p></td>
<td><p>k,r0,epsilon,sigma,shift</p></td>
<td><p>type bonds</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="bond_fene.html"><span class="doc">fene/nm</span></a></p></td>
<td><p>k,r0</p></td>
<td><p>type bonds</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="bond_gaussian.html"><span class="doc">gaussian</span></a></p></td>
<td><p>alpha,width,r0</p></td>
<td><p>type bonds</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="bond_gromos.html"><span class="doc">gromos</span></a></p></td>
<td><p>k,r0</p></td>
<td><p>type bonds</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="bond_harmonic.html"><span class="doc">harmonic</span></a></p></td>
<td><p>k,r0</p></td>
<td><p>type bonds</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="bond_harmonic_restrain.html"><span class="doc">harmonic/restrain</span></a></p></td>
<td><p>k</p></td>
<td><p>type bonds</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="bond_harmonic_shift.html"><span class="doc">harmonic/shift</span></a></p></td>
<td><p>k,r0,r1</p></td>
<td><p>type bonds</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="bond_harmonic_shift_cut.html"><span class="doc">harmonic/shift/cut</span></a></p></td>
<td><p>k,r0,r1</p></td>
<td><p>type bonds</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="bond_mm3.html"><span class="doc">mm3</span></a></p></td>
<td><p>k,r0</p></td>
<td><p>type bonds</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="bond_morse.html"><span class="doc">morse</span></a></p></td>
<td><p>d0,alpha,r0</p></td>
<td><p>type bonds</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="bond_nonlinear.html"><span class="doc">nonlinear</span></a></p></td>
<td><p>lamda,epsilon,r0</p></td>
<td><p>type bonds</p></td>
</tr>
</tbody>
</table>
<hr class="docutils" />
<div class="versionadded">
<p><span class="versionmodified added">Added in version 4May2022.</span></p>
</div>
<p>The <em>angle</em> keyword uses the specified variable to change the value of
an angle coefficient over time, very similar to how the <em>pair</em> keyword
operates. The only difference is that now an angle coefficient for a
given angle type is adapted.</p>
<p>A wild-card asterisk can be used in place of or in conjunction with the
angle type argument to set the coefficients for multiple angle types.
This takes the form “*” or “*n” or “m*” or “m*n”. If <span class="math notranslate nohighlight">\(N\)</span> is
the number of angle types, then an asterisk with no numeric values means
all types from 1 to <span class="math notranslate nohighlight">\(N\)</span>. A leading asterisk means all types from
1 to n (inclusive). A trailing asterisk means all types from m to
<span class="math notranslate nohighlight">\(N\)</span> (inclusive). A middle asterisk means all types from m to n
(inclusive).</p>
<p>If <a class="reference internal" href="angle_hybrid.html"><span class="doc">angle_style hybrid</span></a> is used, <em>astyle</em> should be a
sub-style name. The angle styles that currently work with fix adapt are:</p>
<table class="docutils align-default">
<tbody>
<tr class="row-odd"><td><p><a class="reference internal" href="angle_harmonic.html"><span class="doc">harmonic</span></a></p></td>
<td><p>k,theta0</p></td>
<td><p>type angles</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="angle_charmm.html"><span class="doc">charmm</span></a></p></td>
<td><p>k,theta0</p></td>
<td><p>type angles</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="angle_class2.html"><span class="doc">class2</span></a></p></td>
<td><p>k2,k3,k4,theta0</p></td>
<td><p>type angles</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="angle_cosine.html"><span class="doc">cosine</span></a></p></td>
<td><p>k</p></td>
<td><p>type angles</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="angle_cosine_delta.html"><span class="doc">cosine/delta</span></a></p></td>
<td><p>k</p></td>
<td><p>type angles</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="angle_cosine_periodic.html"><span class="doc">cosine/periodic</span></a></p></td>
<td><p>k,b,n</p></td>
<td><p>type angles</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="angle_cosine_squared.html"><span class="doc">cosine/squared</span></a></p></td>
<td><p>k,theta0</p></td>
<td><p>type angles</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="angle_cosine_squared_restricted.html"><span class="doc">cosine/squared/restricted</span></a></p></td>
<td><p>k,theta0</p></td>
<td><p>type angles</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="angle_dipole.html"><span class="doc">dipole</span></a></p></td>
<td><p>k,gamma0</p></td>
<td><p>type angles</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="angle_fourier.html"><span class="doc">fourier</span></a></p></td>
<td><p>k,c0,c1,c2</p></td>
<td><p>type angles</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="angle_fourier_simple.html"><span class="doc">fourier/simple</span></a></p></td>
<td><p>k,c,n</p></td>
<td><p>type angles</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="angle_gaussian.html"><span class="doc">gaussian</span></a></p></td>
<td><p>alpha,width,theta0</p></td>
<td><p>type angles</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="angle_mm3.html"><span class="doc">mm3</span></a></p></td>
<td><p>k,theta0</p></td>
<td><p>type angles</p></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="angle_quartic.html"><span class="doc">quartic</span></a></p></td>
<td><p>k2,k3,k4,theta0</p></td>
<td><p>type angles</p></td>
</tr>
<tr class="row-odd"><td><p><a class="reference internal" href="angle_spica.html"><span class="doc">spica</span></a></p></td>
<td><p>k,theta0</p></td>
<td><p>type angles</p></td>
</tr>
</tbody>
</table>
<p>Note that internally, theta0 is stored in radians, so the variable
this fix uses to reset theta0 needs to generate values in radians.</p>
<hr class="docutils" />
<p>The <em>kspace</em> keyword used the specified variable as a scale factor on
the energy, forces, virial calculated by whatever <span class="math notranslate nohighlight">\(k\)</span>-space solver is
defined by the <a class="reference internal" href="kspace_style.html"><span class="doc">kspace_style</span></a> command. If the
variable has a value of 1.0, then the solver is unaltered.</p>
<p>The <em>kspace</em> keyword works this way whether the <em>scale</em> keyword
is set to <em>no</em> or <em>yes</em>.</p>
<hr class="docutils" />
<p>The <em>atom</em> keyword enables various atom properties to be changed. The
<em>aparam</em> argument is the name of the parameter to change. This is the
current list of atom parameters that can be varied by this fix:</p>
<ul class="simple">
<li><p>charge = charge on particle</p></li>
<li><p>diameter or diameter/disc = diameter of particle</p></li>
</ul>
<p>The <em>v_name</em> argument of the <em>atom</em> keyword is the name of an
<a class="reference internal" href="variable.html"><span class="doc">equal-style variable</span></a> which will be evaluated each
time this fix is invoked to set, or scale the parameter to a new
value. It should be specified as v_name, where name is the variable
name. See the discussion above describing the formulas associated
with equal-style variables. The new value is assigned to the
corresponding attribute for all atoms in the fix group.</p>
<p>If the atom parameter is <em>diameter</em> and per-atom density and per-atom
mass are defined for particles (e.g., <a class="reference internal" href="atom_style.html"><span class="doc">atom_style granular</span></a>), then the mass of each particle is, by default, also
changed when the diameter changes. The mass is set from the particle
volume for 3d systems (density is assumed to stay constant). For 2d,
the default is for LAMMPS to model particles with a radius attribute
as spheres. However, if the atom parameter is <em>diameter/disc</em>, then the
mass is set from the particle area (the density is assumed to be in
mass/distance<span class="math notranslate nohighlight">\(^2\)</span> units). The mass of the particle may also be kept
constant if the <em>mass</em> keyword is set to <em>no</em>. This can be useful to account
for diameter changes that do not involve mass changes (e.g., thermal
expansion).</p>
<p>For example, these commands would shrink the diameter of all granular
particles in the “center” group from 1.0 to 0.1 in a linear fashion
over the course of a 1000-step simulation:</p>
<div class="highlight-LAMMPS notranslate"><div class="highlight"><pre><span></span><span class="k">variable </span><span class="nv nv-Identifier">size</span><span class="w"> </span><span class="n">equal</span><span class="w"> </span><span class="n">ramp</span><span class="nv">(1.0,0.1)</span>
<span class="k">fix </span><span class="nv nv-Identifier">1</span><span class="w"> </span><span class="nv nv-Identifier">center</span><span class="w"> </span><span class="n">adapt</span><span class="w"> </span><span class="m">10</span><span class="w"> </span><span class="n">atom</span><span class="w"> </span><span class="n">diameter</span><span class="w"> </span><span class="n">v_size</span>
</pre></div>
</div>
<hr class="docutils" />
<p>This fix can be used in long simulations which are restarted one or
more times to continuously adapt simulation parameters, but it must be
done carefully. There are two issues to consider. The first is how
to adapt the parameters in a continuous manner from one simulation to
the next. The second is how, if desired, to reset the parameters to
their original values at the end of the last restarted run.</p>
<p>Note that all the parameters changed by this fix are written into a
restart file in their current changed state. A new restarted
simulation does not know the original time=0 values, unless the
input script explicitly resets the parameters (after the restart file
is read) to the original values.</p>
<p>Also note that the time-dependent variable(s) used in the restart
script should typically be written as a function of time elapsed since
the original simulation began.</p>
<p>With this in mind, if the <em>scale</em> keyword is set to <em>no</em> (the default)
in a restarted simulation, original parameters are not needed. The
adapted parameters should seamlessly continue their variation relative
to the preceding simulation.</p>
<p>If the <em>scale</em> keyword is set to <em>yes</em>, then the input script should
typically reset the parameters being adapted to their original values,
so that the scaling formula specified by the variable will operate
correctly. An exception is if the <em>atom</em> keyword is being used with
<em>scale yes</em>. In this case, information is added to the restart file
so that per-atom properties in the new run will automatically be
scaled relative to their original values. This will only work if the
fix adapt command specified in the restart script has the same ID as
the one used in the original script.</p>
<p>In a restarted run, if the <em>reset</em> keyword is set to <em>yes</em>, and the
run ends in this script (as opposed to just writing more restart
files), parameters will be restored to the values they were at the
beginning of the run command in the restart script, which as
explained above, may or may not be the original values of the
parameters. Again, an exception is if the <em>atom</em> keyword is being
used with <em>reset yes</em> (in all the runs). In that case, the original
per-atom parameters are stored in the restart file, and will be
restored when the restarted run finally completes.</p>
</section>
<hr class="docutils" />
<section id="restart-fix-modify-output-run-start-stop-minimize-info">
<h2>Restart, fix_modify, output, run start/stop, minimize info<a class="headerlink" href="#restart-fix-modify-output-run-start-stop-minimize-info" title="Link to this heading"></a></h2>
<p>If the <em>atom</em> keyword is used and the <em>scale</em> or <em>reset</em> keyword is
set to <em>yes</em>, then this fix writes information to a restart file so
that in a restarted run scaling can continue in a seamless manner
and/or the per-atom values can be restored, as explained above.</p>
<p>None of the <a class="reference internal" href="fix_modify.html"><span class="doc">fix_modify</span></a> options are relevant to
this fix. No global or per-atom quantities are stored by this fix for
access by various <a class="reference internal" href="Howto_output.html"><span class="doc">output commands</span></a>. No parameter
of this fix can be used with the <em>start/stop</em> keywords of the
<a class="reference internal" href="run.html"><span class="doc">run</span></a> command. This fix is not invoked during <a class="reference internal" href="minimize.html"><span class="doc">energy
minimization</span></a>.</p>
<p>For <a class="reference internal" href="run_style.html"><span class="doc">rRESPA time integration</span></a>, this fix changes
parameters on the outermost rRESPA level.</p>
</section>
<section id="restrictions">
<h2>Restrictions<a class="headerlink" href="#restrictions" title="Link to this heading"></a></h2>
<blockquote>
<div><p>none</p>
</div></blockquote>
</section>
<section id="related-commands">
<h2>Related commands<a class="headerlink" href="#related-commands" title="Link to this heading"></a></h2>
<p><a class="reference internal" href="compute_ti.html"><span class="doc">compute ti</span></a>, <a class="reference internal" href="fix_adapt_fep.html"><span class="doc">fix adapt/fep</span></a></p>
</section>
<section id="default">
<h2>Default<a class="headerlink" href="#default" title="Link to this heading"></a></h2>
<p>The option defaults are scale = no, reset = no, mass = yes.</p>
</section>
</section>
</div>
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