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<title>fix bond/create 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="Library.html">1. LAMMPS Library Interfaces</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"><a class="reference internal" href="fix_adapt.html">fix adapt command</a></li>
<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 current"><a class="current reference internal" href="#">fix bond/create command</a></li>
<li class="toctree-l2"><a class="reference internal" href="#fix-bond-create-angle-command">fix bond/create/angle command</a><ul>
<li class="toctree-l3"><a class="reference internal" href="#syntax">Syntax</a></li>
<li class="toctree-l3"><a class="reference internal" href="#examples">Examples</a></li>
<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>
</ul>
</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>
<li class="toctree-l2"><a class="reference internal" href="fix_pimdb.html#fix-pimdb-nvt-command">fix pimdb/nvt command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_planeforce.html">fix planeforce command</a></li>
<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>
<li class="toctree-l2"><a class="reference internal" href="fix_polarize.html#fix-polarize-bem-icc-command">fix polarize/bem/icc command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_polarize.html#fix-polarize-functional-command">fix polarize/functional command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_pour.html">fix pour command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_precession_spin.html">fix precession/spin command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_press_berendsen.html">fix press/berendsen command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_press_langevin.html">fix press/langevin command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_print.html">fix print command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_propel_self.html">fix propel/self command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_property_atom.html">fix property/atom command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_python_invoke.html">fix python/invoke command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_python_move.html">fix python/move command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_qbmsst.html">fix qbmsst command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_qeq.html">fix qeq/point command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_qeq.html#fix-qeq-shielded-command">fix qeq/shielded command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_qeq.html#fix-qeq-slater-command">fix qeq/slater command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_qeq.html#fix-qeq-ctip-command">fix qeq/ctip command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_qeq.html#fix-qeq-dynamic-command">fix qeq/dynamic command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_qeq.html#fix-qeq-fire-command">fix qeq/fire command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_qeq_comb.html">fix qeq/comb command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_qeq_reaxff.html">fix qeq/reaxff command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_qmmm.html">fix qmmm command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_qtb.html">fix qtb command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_qtpie_reaxff.html">fix qtpie/reaxff command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_reaxff_bonds.html">fix reaxff/bonds command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_reaxff_species.html">fix reaxff/species command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_recenter.html">fix recenter command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_restrain.html">fix restrain command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_rheo.html">fix rheo command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_rheo_oxidation.html">fix rheo/oxidation command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_rheo_pressure.html">fix rheo/pressure command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_rheo_thermal.html">fix rheo/thermal command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_rheo_viscosity.html">fix rheo/viscosity command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_rhok.html">fix rhok command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_rigid.html">fix rigid command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_rigid.html#fix-rigid-nve-command">fix rigid/nve command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_rigid.html#fix-rigid-nph-command">fix rigid/nph command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_rigid.html#fix-rigid-small-command">fix rigid/small command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_rigid.html#fix-rigid-nve-small-command">fix rigid/nve/small command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_rigid_meso.html">fix rigid/meso command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_rx.html">fix rx command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_saed_vtk.html">fix saed/vtk command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_setforce.html">fix setforce command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_setforce.html#fix-setforce-spin-command">fix setforce/spin command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_sgcmc.html">fix sgcmc command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_shake.html">fix shake command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_shake.html#fix-rattle-command">fix rattle command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_shardlow.html">fix shardlow command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_smd.html">fix smd command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_smd_adjust_dt.html">fix smd/adjust_dt command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_smd_integrate_tlsph.html">fix smd/integrate_tlsph command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_smd_integrate_ulsph.html">fix smd/integrate_ulsph command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_smd_move_triangulated_surface.html">fix smd/move_tri_surf command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_smd_setvel.html">fix smd/setvel command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_smd_wall_surface.html">fix smd/wall_surface command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_sph.html">fix sph command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_sph_stationary.html">fix sph/stationary command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_spring.html">fix spring command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_spring_chunk.html">fix spring/chunk command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_spring_rg.html">fix spring/rg command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_spring_self.html">fix spring/self command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_srd.html">fix srd command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_store_force.html">fix store/force command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_store_state.html">fix store/state command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_temp_berendsen.html">fix temp/berendsen command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_temp_csvr.html">fix temp/csvr command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_temp_csvr.html#fix-temp-csld-command">fix temp/csld command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_temp_rescale.html">fix temp/rescale command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_temp_rescale_eff.html">fix temp/rescale/eff command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_tfmc.html">fix tfmc command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_tgnh_drude.html">fix tgnvt/drude command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_tgnh_drude.html#fix-tgnpt-drude-command">fix tgnpt/drude command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_thermal_conductivity.html">fix thermal/conductivity command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_ti_spring.html">fix ti/spring command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_tmd.html">fix tmd command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_ttm.html">fix ttm command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_ttm.html#fix-ttm-grid-command">fix ttm/grid command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_ttm.html#fix-ttm-mod-command">fix ttm/mod command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_tune_kspace.html">fix tune/kspace command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_vector.html">fix vector command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_viscosity.html">fix viscosity command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_viscous.html">fix viscous command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_viscous_sphere.html">fix viscous/sphere command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_wall.html">fix wall/lj93 command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_wall.html#fix-wall-lj126-command">fix wall/lj126 command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_wall.html#fix-wall-lj1043-command">fix wall/lj1043 command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_wall.html#fix-wall-colloid-command">fix wall/colloid command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_wall.html#fix-wall-harmonic-command">fix wall/harmonic command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_wall.html#fix-wall-lepton-command">fix wall/lepton command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_wall.html#fix-wall-morse-command">fix wall/morse command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_wall_body_polygon.html">fix wall/body/polygon command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_wall_body_polyhedron.html">fix wall/body/polyhedron command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_wall_ees.html">fix wall/ees command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_wall_ees.html#fix-wall-region-ees-command">fix wall/region/ees command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_wall_flow.html">fix wall/flow command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_wall_gran.html">fix wall/gran command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_wall_gran_region.html">fix wall/gran/region command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_wall_piston.html">fix wall/piston command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_wall_reflect.html">fix wall/reflect command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_wall_reflect_stochastic.html">fix wall/reflect/stochastic command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_wall_region.html">fix wall/region command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_wall_srd.html">fix wall/srd command</a></li>
<li class="toctree-l2"><a class="reference internal" href="fix_widom.html">fix widom command</a></li>
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<li class="toctree-l1"><a class="reference internal" href="computes.html">Compute Styles</a></li>
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<p><span class="math notranslate nohighlight">\(\renewcommand{\AA}{\text{Å}}\)</span></p>
<section id="fix-bond-create-command">
<span id="index-1"></span><span id="index-0"></span><h1>fix bond/create command<a class="headerlink" href="#fix-bond-create-command" title="Link to this heading"></a></h1>
</section>
<section id="fix-bond-create-angle-command">
<h1>fix bond/create/angle command<a class="headerlink" href="#fix-bond-create-angle-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">style</span><span class="w"> </span><span class="n">Nevery</span><span class="w"> </span><span class="n">itype</span><span class="w"> </span><span class="n">jtype</span><span class="w"> </span><span class="n">Rmin</span><span class="w"> </span><span class="n">bondtype</span><span class="w"> </span><span class="n">keyword</span><span class="w"> </span><span class="n">values</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>style = <em>bond/create</em> or <em>bond/create/angle</em></p></li>
<li><p>Nevery = attempt bond creation every this many steps</p></li>
<li><p>itype,jtype = atoms of itype can bond to atoms of jtype (1-Ntypes or type label)</p></li>
<li><p>Rmin = two atoms separated by less than Rmin can bond (distance units)</p></li>
<li><p>bondtype = type of created bonds (integer or type label)</p></li>
<li><p>zero or more keyword/value pairs may be appended to args</p></li>
<li><p>keyword = <em>iparam</em> or <em>jparam</em> or <em>prob</em> or <em>atype</em> or <em>dtype</em> or <em>itype</em> or <em>aconstrain</em></p>
<pre class="literal-block"><em>iparam</em> values = maxbond, newtype
maxbond = max # of bonds of bondtype the itype atom can have
newtype = change the itype atom to this type when maxbonds exist (1-Ntypes or type label)
<em>jparam</em> values = maxbond, newtype
maxbond = max # of bonds of bondtype the jtype atom can have
newtype = change the jtype atom to this type when maxbonds exist (1-Ntypes or type label)
<em>prob</em> values = fraction seed
fraction = create a bond with this probability if otherwise eligible
seed = random number seed (positive integer)
<em>atype</em> value = angletype
angletype = type of created angles (integer or type label)
<em>dtype</em> value = dihedraltype
dihedraltype = type of created dihedrals (integer or type label)
<em>itype</em> value = impropertype
impropertype = type of created impropers (integer or type label)
<em>aconstrain</em> value = amin amax
amin = minimal angle at which new bonds can be created
amax = maximal angle at which new bonds can be created</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">5</span><span class="w"> </span><span class="nv nv-Identifier">all</span><span class="w"> </span><span class="n">bond</span><span class="o">/</span><span class="n">create</span><span class="w"> </span><span class="m">10</span><span class="w"> </span><span class="m">1</span><span class="w"> </span><span class="m">2</span><span class="w"> </span><span class="m">0.8</span><span class="w"> </span><span class="m">1</span>
<span class="k">fix </span><span class="nv nv-Identifier">5</span><span class="w"> </span><span class="nv nv-Identifier">all</span><span class="w"> </span><span class="n">bond</span><span class="o">/</span><span class="n">create</span><span class="w"> </span><span class="m">1</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="m">0.8</span><span class="w"> </span><span class="m">1</span><span class="w"> </span><span class="n">prob</span><span class="w"> </span><span class="m">0.5</span><span class="w"> </span><span class="m">85784</span><span class="w"> </span><span class="n">iparam</span><span class="w"> </span><span class="m">2</span><span class="w"> </span><span class="m">3</span>
<span class="k">fix </span><span class="nv nv-Identifier">5</span><span class="w"> </span><span class="nv nv-Identifier">all</span><span class="w"> </span><span class="n">bond</span><span class="o">/</span><span class="n">create</span><span class="w"> </span><span class="m">1</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="m">0.8</span><span class="w"> </span><span class="m">1</span><span class="w"> </span><span class="n">prob</span><span class="w"> </span><span class="m">0.5</span><span class="w"> </span><span class="m">85784</span><span class="w"> </span><span class="n">iparam</span><span class="w"> </span><span class="m">2</span><span class="w"> </span><span class="m">3</span><span class="w"> </span><span class="n">atype</span><span class="w"> </span><span class="m">1</span><span class="w"> </span><span class="n">dtype</span><span class="w"> </span><span class="m">2</span>
<span class="k">fix </span><span class="nv nv-Identifier">5</span><span class="w"> </span><span class="nv nv-Identifier">all</span><span class="w"> </span><span class="n">bond</span><span class="o">/</span><span class="n">create</span><span class="o">/</span><span class="n">angle</span><span class="w"> </span><span class="m">10</span><span class="w"> </span><span class="m">1</span><span class="w"> </span><span class="m">2</span><span class="w"> </span><span class="m">1.122</span><span class="w"> </span><span class="m">1</span><span class="w"> </span><span class="n">aconstrain</span><span class="w"> </span><span class="m">120</span><span class="w"> </span><span class="m">180</span><span class="w"> </span><span class="n">prob</span><span class="w"> </span><span class="m">1</span><span class="w"> </span><span class="m">4928459</span><span class="w"> </span><span class="n">iparam</span><span class="w"> </span><span class="m">2</span><span class="w"> </span><span class="m">1</span><span class="w"> </span><span class="n">jparam</span><span class="w"> </span><span class="m">2</span><span class="w"> </span><span class="m">2</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="w"> </span><span class="m">2</span><span class="w"> </span><span class="n">n2</span>
<span class="k">labelmap</span><span class="w"> </span><span class="n">bond</span><span class="w"> </span><span class="m">1</span><span class="w"> </span><span class="n">c1</span><span class="o">-</span><span class="n">n2</span>
<span class="k">fix </span><span class="nv nv-Identifier">5</span><span class="w"> </span><span class="nv nv-Identifier">all</span><span class="w"> </span><span class="n">bond</span><span class="o">/</span><span class="n">create</span><span class="w"> </span><span class="m">10</span><span class="w"> </span><span class="n">c1</span><span class="w"> </span><span class="n">n2</span><span class="w"> </span><span class="m">0.8</span><span class="w"> </span><span class="n">c1</span><span class="o">-</span><span class="n">n2</span>
</pre></div>
</div>
</section>
<section id="description">
<h2>Description<a class="headerlink" href="#description" title="Link to this heading"></a></h2>
<p>Create bonds between pairs of atoms as a simulation runs according to
specified criteria. This can be used to model the cross-linking of
polymers, the formation of a percolation network, etc. In this
context, a bond means an interaction between a pair of atoms computed
by the <a class="reference internal" href="bond_style.html"><span class="doc">bond_style</span></a> command. Once the bond is created
it will be permanently in place. Optionally, the creation of a bond
can also create angle, dihedral, and improper interactions that the bond
is part of. See the discussion of the <em>atype</em>, <em>dtype</em>, and <em>itype</em>
keywords below.</p>
<p>This process is different than a <a class="reference internal" href="pair_style.html"><span class="doc">pair-wise</span></a> bond-order
potential such as Tersoff or AIREBO, which infer bonds and many-body
interactions based on the current geometry of a small cluster of atoms
and effectively create and destroy bonds and higher-order many-body
interactions from time step to time step as the atoms move.</p>
<p>A check for possible new bonds is performed every <em>Nevery</em> time steps.
If two atoms <span class="math notranslate nohighlight">\(i\)</span> and <span class="math notranslate nohighlight">\(j\)</span> are within a distance <em>Rmin</em> of each
other, atom <span class="math notranslate nohighlight">\(i\)</span> is of type <em>itype</em>, atom <span class="math notranslate nohighlight">\(j\)</span> is of type <em>jtype</em>,
and both <span class="math notranslate nohighlight">\(i\)</span> and <span class="math notranslate nohighlight">\(j\)</span> are in the specified fix group, then if a bond
does not already exist between atoms <span class="math notranslate nohighlight">\(i\)</span> and <span class="math notranslate nohighlight">\(j\)</span>, and if both
<span class="math notranslate nohighlight">\(i\)</span> and <span class="math notranslate nohighlight">\(j\)</span> meet their respective <em>maxbond</em> requirements (explained
below), then <span class="math notranslate nohighlight">\(i\)</span> and <span class="math notranslate nohighlight">\(j\)</span> are labeled as a “possible” bond pair.</p>
<p>If several atoms are close to an atom, it may have multiple possible
bond partners. Every atom checks its list of possible bond partners
and labels the closest such partner as its “sole” bond partner. After
this is done, if atom <span class="math notranslate nohighlight">\(i\)</span> has atom <span class="math notranslate nohighlight">\(j\)</span> as its sole partner and
atom <span class="math notranslate nohighlight">\(j\)</span> has atom <span class="math notranslate nohighlight">\(i\)</span> as its sole partner, then the
<span class="math notranslate nohighlight">\(i,j\)</span> bond is “eligible” to be formed.</p>
<p>Note that these rules mean that an atom will only be part of at most one
created bond on a given time step. It also means that if atom <span class="math notranslate nohighlight">\(i\)</span>
chooses atom <span class="math notranslate nohighlight">\(j\)</span> as its sole partner, but atom <span class="math notranslate nohighlight">\(j\)</span> chooses atom
<span class="math notranslate nohighlight">\(k\)</span> as its sole partner (because <span class="math notranslate nohighlight">\(R_{jk} &lt; R_{ij}\)</span>), then atom
<span class="math notranslate nohighlight">\(i\)</span> will not form a bond on this time step, even if it has other possible
bond partners.</p>
<p>It is permissible to have <em>itype</em> = <em>jtype</em>. <em>Rmin</em> must be <span class="math notranslate nohighlight">\(\leq\)</span> the
pair-wise cutoff distance between <em>itype</em> and <em>jtype</em> atoms, as defined
by the <a class="reference internal" href="pair_style.html"><span class="doc">pair_style</span></a> command.</p>
<p>The <em>iparam</em> and <em>jparam</em> keywords can be used to limit the bonding
functionality of the participating atoms. Each atom keeps track of
how many bonds of <em>bondtype</em> it already has. If atom <span class="math notranslate nohighlight">\(i\)</span> of type
<em>itype</em> already has <em>maxbond</em> bonds (as set by the <em>iparam</em>
keyword), then it will not form any more, and likewise for atom <span class="math notranslate nohighlight">\(j\)</span>.
If <em>maxbond</em> is set to 0, then there is no limit on the number of bonds
that can be formed with that atom.</p>
<p>The <em>newtype</em> value for <em>iparam</em> and <em>jparam</em> can be used to change
the atom type of atom <span class="math notranslate nohighlight">\(i\)</span> or <span class="math notranslate nohighlight">\(j\)</span> when it reaches <em>maxbond</em> number
of bonds of type <em>bondtype</em>. This means it can now interact in a pair-wise
fashion with other atoms in a different way by specifying different
<a class="reference internal" href="pair_coeff.html"><span class="doc">pair_coeff</span></a> coefficients. If you do not wish the
atom type to change, simply specify <em>newtype</em> as <em>itype</em> or <em>jtype</em>.</p>
<p>The <em>prob</em> keyword can also affect whether an eligible bond is
actually created. The <em>fraction</em> setting must be a value between 0.0
and 1.0. A uniform random number between 0.0 and 1.0 is generated and
the eligible bond is only created if the random number is less than <em>fraction</em>.</p>
<p>The <em>aconstrain</em> keyword is only available with the fix
bond/create/angle command. It allows one to specify minimum and maximum
angles <em>amin</em> and <em>amax</em>, respectively, between the two prospective bonding
partners and a third particle that is already bonded to one of the two
partners. Such a criterion can be important when new angles are defined
together with the formation of a new bond. Without a restriction on the
permissible angle, and for stiffer angle potentials, very large energies
can arise and lead to unphysical behavior.</p>
<p>Any bond that is created is assigned a bond type of <em>bondtype</em>.</p>
<p>When a bond is created, data structures within LAMMPS that store bond
topologies are updated to reflect the creation. If the bond is part of
new 3-body (angle) or 4-body (dihedral, improper) interactions, you
can choose to create new angles, dihedrals, and impropers as well using
the <em>atype</em>, <em>dtype</em>, and <em>itype</em> keywords. All of these changes
typically affect pair-wise interactions between atoms that are now part
of new bonds, angles, etc.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>One data structure that is not updated when a bond breaks are
the molecule IDs stored by each atom. Even though two molecules
become one molecule due to the created bond, all atoms in the new
molecule retain their original molecule IDs.</p>
</div>
<p>If the <em>atype</em> keyword is used and if an angle potential is defined
via the <a class="reference internal" href="angle_style.html"><span class="doc">angle_style</span></a> command, then any new 3-body
interactions inferred by the creation of a bond will create new angles
of type <em>angletype</em>, with parameters assigned by the corresponding
<a class="reference internal" href="angle_coeff.html"><span class="doc">angle_coeff</span></a> command. Likewise, the <em>dtype</em> and
<em>itype</em> keywords will create new dihedrals and impropers of type
<em>dihedraltype</em> and <em>impropertype</em>.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>To create a new bond, the internal LAMMPS data structures that
store this information must have space for it. When LAMMPS is
initialized from a data file, the list of bonds is scanned and the
maximum number of bonds per atom is tallied. If some atom will
acquire more bonds than this limit as this fix operates, then the
“extra bond per atom” parameter must be set to allow for it. Ditto
for “extra angle per atom”, “extra dihedral per atom”, and “extra
improper per atom” if angles, dihedrals, or impropers are being added
when bonds are created. See the <a class="reference internal" href="read_data.html"><span class="doc">read_data</span></a> or
<a class="reference internal" href="create_box.html"><span class="doc">create_box</span></a> command for more details. Note that a
data file with no atoms can be used if you wish to add non-bonded
atoms via the <a class="reference internal" href="create_atoms.html"><span class="doc">create atoms</span></a> command (e.g., for a
percolation simulation).</p>
</div>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>LAMMPS stores and maintains a data structure with a list of the
first, second, and third neighbors of each atom (within the bond topology of
the system) for use in weighting pair-wise interactions for bonded
atoms. Note that adding a single bond always adds a new first neighbor
but may also induce <strong>many</strong> new second and third neighbors, depending on the
molecular topology of your system. The “extra special per atom”
parameter must typically be set to allow for the new maximum total
size (first + second + third neighbors) of this per-atom list. There are two
ways to do this. See the <a class="reference internal" href="read_data.html"><span class="doc">read_data</span></a> or
<a class="reference internal" href="create_box.html"><span class="doc">create_box</span></a> commands for details.</p>
</div>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>Even if you do not use the <em>atype</em>, <em>dtype</em>, or <em>itype</em>
keywords, the list of topological neighbors is updated for atoms
affected by the new bond. This in turn affects which neighbors are
considered for pair-wise interactions, using the weighting rules set by
the <a class="reference internal" href="special_bonds.html"><span class="doc">special_bonds</span></a> command. Consider a new bond
created between atoms <span class="math notranslate nohighlight">\(i\)</span> and <span class="math notranslate nohighlight">\(j\)</span>. If <span class="math notranslate nohighlight">\(j\)</span> has a bonded
neighbor <span class="math notranslate nohighlight">\(k\)</span>, then <span class="math notranslate nohighlight">\(k\)</span> becomes a second neighbor of <span class="math notranslate nohighlight">\(i\)</span>.
Even if the <em>atype</em> keyword is not used to create angle <span class="math notranslate nohighlight">\(\angle ijk\)</span>,
the pair-wise interaction between <span class="math notranslate nohighlight">\(i\)</span> and <span class="math notranslate nohighlight">\(k\)</span> could potentially
be turned off or weighted by the 13 weighting specified
by the <a class="reference internal" href="special_bonds.html"><span class="doc">special_bonds</span></a> command. This is the case
even if the “angle yes” option was used with that command. The same
is true for third neighbors (14 interactions), the <em>dtype</em> keyword, and
the “dihedral yes” option used with the
<a class="reference internal" href="special_bonds.html"><span class="doc">special_bonds</span></a> command.</p>
</div>
<p>Note that even if your simulation starts with no bonds, you must
define a <a class="reference internal" href="bond_style.html"><span class="doc">bond_style</span></a> and use the
<a class="reference internal" href="bond_coeff.html"><span class="doc">bond_coeff</span></a> command to specify coefficients for the
<em>bondtype</em>. Similarly, if new atom types are specified by the
<em>iparam</em> or <em>jparam</em> keywords, they must be within the range of atom
types allowed by the simulation and pair-wise coefficients must be
specified for the new types.</p>
<p>Computationally, each time step this fix is invoked, it loops over
neighbor lists and computes distances between pairs of atoms in the
list. It also communicates between neighboring processors to
coordinate which bonds are created. Moreover, if any bonds are
created, neighbor lists must be immediately updated on the same
time step. This is to ensure that any pair-wise interactions that
should be turned “off” due to a bond creation, because they are now
excluded by the presence of the bond and the settings of the
<a class="reference internal" href="special_bonds.html"><span class="doc">special_bonds</span></a> command, will be immediately
recognized. All of these operations increase the cost of a time step.
Thus, you should be cautious about invoking this fix too frequently.</p>
<p>You can dump out snapshots of the current bond topology via the <a class="reference internal" href="dump.html"><span class="doc">dump local</span></a> command.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>Creating a bond typically alters the energy of a system. You
should be careful not to choose bond creation criteria that induce a
dramatic change in energy. For example, if you define a very stiff
harmonic bond and create it when two atoms are separated by a distance
far from the equilibrium bond length, then the two atoms will oscillate
dramatically when the bond is formed. More generally, you may need to
thermostat your system to compensate for energy changes resulting from
created bonds (and angles, dihedrals, impropers).</p>
</div>
</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>No information about this fix is written to <a class="reference internal" href="restart.html"><span class="doc">binary restart files</span></a>. None of the <a class="reference internal" href="fix_modify.html"><span class="doc">fix_modify</span></a> options are
relevant to this fix.</p>
<p>This fix computes two statistics which it stores in a global vector of
length 2, which can be accessed by various <a class="reference internal" href="Howto_output.html"><span class="doc">output commands</span></a>. The vector values calculated by this fix are
“intensive”.</p>
<p>The two quantities in the global vector are</p>
<blockquote>
<div><ol class="arabic simple">
<li><p>number of bonds created on the most recent creation time step</p></li>
<li><p>cumulative number of bonds created</p></li>
</ol>
</div></blockquote>
<p>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>
</section>
<section id="restrictions">
<h2>Restrictions<a class="headerlink" href="#restrictions" title="Link to this heading"></a></h2>
<p>This fix is part of the MC package. It is only enabled if LAMMPS was
built with that package. See the <a class="reference internal" href="Build_package.html"><span class="doc">Build package</span></a>
doc page for more info.</p>
</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="fix_bond_break.html"><span class="doc">fix bond/break</span></a>, <a class="reference internal" href="fix_bond_react.html"><span class="doc">fix bond/react</span></a>, <a class="reference internal" href="fix_bond_swap.html"><span class="doc">fix bond/swap</span></a>,
<a class="reference internal" href="dump.html"><span class="doc">dump local</span></a>, <a class="reference internal" href="special_bonds.html"><span class="doc">special_bonds</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 iparam = (0,itype), jparam = (0,jtype), and
prob = 1.0.</p>
</section>
</section>
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