765 lines
53 KiB
HTML
765 lines
53 KiB
HTML
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<title>fix ave/correlate command — LAMMPS documentation</title>
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<a href="Manual.html" class="icon icon-home"> LAMMPS
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<li class="toctree-l1"><a class="reference internal" href="Section_commands.html">3. Commands</a></li>
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<li class="toctree-l1"><a class="reference internal" href="Section_packages.html">4. Packages</a></li>
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<li class="toctree-l1"><a class="reference internal" href="Section_accelerate.html">5. Accelerating LAMMPS performance</a></li>
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<li class="toctree-l1"><a class="reference internal" href="Section_perf.html">8. Performance & scalability</a></li>
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<li class="toctree-l1"><a class="reference internal" href="Section_modify.html">10. Modifying & extending LAMMPS</a></li>
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<li class="toctree-l1"><a class="reference internal" href="Section_python.html">11. Python interface to LAMMPS</a></li>
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<li class="toctree-l1"><a class="reference internal" href="Section_errors.html">12. Errors</a></li>
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<li class="toctree-l1"><a class="reference internal" href="Section_history.html">13. Future and history</a></li>
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<p class="caption"><span class="caption-text">Index</span></p>
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<ul class="current">
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<li class="toctree-l1"><a class="reference internal" href="tutorials.html">Tutorials</a></li>
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<li class="toctree-l1"><a class="reference internal" href="commands.html">Commands</a></li>
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<li class="toctree-l1 current"><a class="reference internal" href="fixes.html">Fixes</a><ul class="current">
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<li class="toctree-l2"><a class="reference internal" href="fix_adapt.html">fix adapt command</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>
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<li class="toctree-l2"><a class="reference internal" href="fix_addforce.html">fix addforce command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_addtorque.html">fix addtorque command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_append_atoms.html">fix append/atoms command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_atc.html">fix atc command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_atom_swap.html">fix atom/swap command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_ave_atom.html">fix ave/atom command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_ave_chunk.html">fix ave/chunk command</a></li>
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<li class="toctree-l2 current"><a class="current reference internal" href="#">fix ave/correlate command</a><ul>
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<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="#examples">Examples</a></li>
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<li class="toctree-l3"><a class="reference internal" href="#description">Description</a></li>
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<li class="toctree-l3"><a class="reference internal" href="#restrictions">Restrictions</a></li>
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<li class="toctree-l3"><a class="reference internal" href="#related-commands">Related commands</a></li>
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</ul>
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</li>
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<li class="toctree-l2"><a class="reference internal" href="fix_ave_correlate_long.html">fix ave/correlate/long command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_ave_histo.html">fix ave/histo command</a></li>
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<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>
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<li class="toctree-l2"><a class="reference internal" href="fix_ave_time.html">fix ave/time command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_aveforce.html">fix aveforce command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_balance.html">fix balance command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_bond_break.html">fix bond/break command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_bond_create.html">fix bond/create command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_bond_swap.html">fix bond/swap command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_box_relax.html">fix box/relax command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_colvars.html">fix colvars command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_controller.html">fix controller command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_deform.html">fix deform command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_deform.html#fix-deform-kk-command">fix deform/kk command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_deposit.html">fix deposit command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_drag.html">fix drag command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_drude.html">fix drude command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_drude_transform.html">fix drude/transform/direct command</a></li>
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<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>
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<li class="toctree-l2"><a class="reference internal" href="fix_dt_reset.html">fix dt/reset command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_efield.html">fix efield command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_ehex.html">fix ehex command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_enforce2d.html">fix enforce2d command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_eos_cv.html">fix eos/cv command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_eos_table.html">fix eos/table command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_eos_table_rx.html">fix eos/table/rx command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_evaporate.html">fix evaporate command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_external.html">fix external command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_flow_gauss.html">fix flow/gauss command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_freeze.html">fix freeze command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_gcmc.html">fix gcmc command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_gld.html">fix gld command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_gle.html">fix gle command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_gravity.html">fix gravity command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_gravity.html#fix-gravity-omp-command">fix gravity/omp command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_heat.html">fix heat command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_imd.html">fix imd command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_indent.html">fix indent command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_ipi.html">fix ipi command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_langevin.html">fix langevin command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_langevin.html#fix-langevin-kk-command">fix langevin/kk command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_langevin_drude.html">fix langevin/drude command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_langevin_eff.html">fix langevin/eff command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_lb_fluid.html">fix lb/fluid command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_lb_momentum.html">fix lb/momentum command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_lb_pc.html">fix lb/pc command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_lb_rigid_pc_sphere.html">fix lb/rigid/pc/sphere command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_lb_viscous.html">fix lb/viscous command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_lineforce.html">fix lineforce command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_manifoldforce.html">fix manifoldforce command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_meso.html">fix meso command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_meso_stationary.html">fix meso/stationary command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_momentum.html">fix momentum command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_move.html">fix move command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_msst.html">fix msst command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_neb.html">fix neb command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nh.html">fix nvt command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nh.html#fix-nvt-intel-command">fix nvt/intel command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nh.html#fix-nvt-kk-command">fix nvt/kk command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nh.html#fix-nvt-omp-command">fix nvt/omp command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nh.html#fix-npt-command">fix npt command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nh.html#fix-npt-intel-command">fix npt/intel command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nh.html#fix-npt-kk-command">fix npt/kk command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nh.html#fix-npt-omp-command">fix npt/omp command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nh.html#fix-nph-command">fix nph command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nh.html#fix-nph-kk-command">fix nph/kk command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nh.html#fix-nph-omp-command">fix nph/omp command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nh_eff.html">fix nvt/eff command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nh_eff.html#fix-npt-eff-command">fix npt/eff command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nh_eff.html#fix-nph-eff-command">fix nph/eff command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nph_asphere.html">fix nph/asphere command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nph_asphere.html#fix-nph-asphere-omp-command">fix nph/asphere/omp command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nph_body.html">fix nph/body command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nph_sphere.html">fix nph/sphere command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nph_sphere.html#fix-nph-sphere-omp-command">fix nph/sphere/omp command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nphug.html">fix nphug command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nphug.html#fix-nphug-omp-command">fix nphug/omp command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_npt_asphere.html">fix npt/asphere command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_npt_asphere.html#fix-npt-asphere-omp-command">fix npt/asphere/omp command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_npt_body.html">fix npt/body command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_npt_sphere.html">fix npt/sphere command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_npt_sphere.html#fix-npt-sphere-omp-command">fix npt/sphere/omp command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nve.html">fix nve command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nve.html#fix-nve-intel-command">fix nve/intel command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nve.html#fix-nve-kk-command">fix nve/kk command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nve.html#fix-nve-omp-command">fix nve/omp command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nve_asphere.html">fix nve/asphere command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nve_asphere.html#fix-nve-asphere-intel-command">fix nve/asphere/intel command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nve_asphere_noforce.html">fix nve/asphere/noforce command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nve_body.html">fix nve/body command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nve_eff.html">fix nve/eff command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nve_limit.html">fix nve/limit command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nve_line.html">fix nve/line command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nve_manifold_rattle.html">fix nve/manifold/rattle command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nve_noforce.html">fix nve/noforce command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nve_sphere.html">fix nve/sphere command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nve_sphere.html#fix-nve-sphere-omp-command">fix nve/sphere/omp command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nve_tri.html">fix nve/tri command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nvt_asphere.html">fix nvt/asphere command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nvt_asphere.html#fix-nvt-asphere-omp-command">fix nvt/asphere/omp command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nvt_body.html">fix nvt/body command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nvt_manifold_rattle.html">fix nvt/manifold/rattle command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nvt_sllod.html">fix nvt/sllod command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nvt_sllod.html#fix-nvt-sllod-intel-command">fix nvt/sllod/intel command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nvt_sllod.html#fix-nvt-sllod-omp-command">fix nvt/sllod/omp command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nvt_sllod_eff.html">fix nvt/sllod/eff command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nvt_sphere.html">fix nvt/sphere command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_nvt_sphere.html#fix-nvt-sphere-omp-command">fix nvt/sphere/omp command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_oneway.html">fix oneway command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_orient.html">fix orient/fcc command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_orient.html#fix-orient-bcc-command">fix orient/bcc command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_phonon.html">fix phonon command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_pimd.html">fix pimd command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_planeforce.html">fix planeforce command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_poems.html">fix poems</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_pour.html">fix pour command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_press_berendsen.html">fix press/berendsen command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_print.html">fix print 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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<li class="toctree-l2"><a class="reference internal" href="fix_qeq.html">fix qeq/point command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_qeq.html#fix-qeq-shielded-command">fix qeq/shielded command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_qeq.html#fix-qeq-slater-command">fix qeq/slater command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_qeq.html#fix-qeq-dynamic-command">fix qeq/dynamic command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_qeq_comb.html">fix qeq/comb command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_qeq_comb.html#fix-qeq-comb-omp-command">fix qeq/comb/omp command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_qeq_reax.html">fix qeq/reax command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_qeq_reax.html#fix-qeq-reax-kk-command">fix qeq/reax/kk command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_qmmm.html">fix qmmm command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_qtb.html">fix qtb command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_reax_bonds.html">fix reax/bonds command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_reax_bonds.html#fix-reax-c-bonds-command">fix reax/c/bonds command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_reaxc_species.html">fix reax/c/species command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_recenter.html">fix recenter command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_restrain.html">fix restrain command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_rigid.html">fix rigid command</a></li>
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<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-nvt-command">fix rigid/nvt 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>
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<li class="toctree-l2"><a class="reference internal" href="fix_rigid.html#fix-rigid-small-command">fix rigid/small command</a></li>
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<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.html#fix-rigid-nvt-small-command">fix rigid/nvt/small command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_rigid.html#fix-rigid-npt-small-command">fix rigid/npt/small command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_rigid.html#fix-rigid-nph-small-command">fix rigid/nph/small command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_saed_vtk.html">fix saed/vtk command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_setforce.html#fix-setforce-kk-command">fix setforce/kk command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_wall.html#fix-wall-lj126-command">fix wall/lj126 command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_wall.html#fix-wall-lj1043-command">fix wall/lj1043 command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_wall.html#fix-wall-colloid-command">fix wall/colloid command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_wall.html#fix-wall-harmonic-command">fix wall/harmonic command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_wall_gran.html">fix wall/gran command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_wall_piston.html">fix wall/piston command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_wall_reflect.html#fix-wall-reflect-kk-command">fix wall/reflect/kk command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_wall_region.html">fix wall/region command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="fix_wall_srd.html">fix wall/srd command</a></li>
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<div class="section" id="fix-ave-correlate-command">
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<span id="index-0"></span><h1>fix ave/correlate command</h1>
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<div class="section" id="syntax">
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<h2>Syntax</h2>
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<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">fix</span> <span class="n">ID</span> <span class="n">group</span><span class="o">-</span><span class="n">ID</span> <span class="n">ave</span><span class="o">/</span><span class="n">correlate</span> <span class="n">Nevery</span> <span class="n">Nrepeat</span> <span class="n">Nfreq</span> <span class="n">value1</span> <span class="n">value2</span> <span class="o">...</span> <span class="n">keyword</span> <span class="n">args</span> <span class="o">...</span>
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</pre></div>
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</div>
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<ul>
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<li><p class="first">ID, group-ID are documented in <a class="reference internal" href="fix.html"><span class="doc">fix</span></a> command</p>
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</li>
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<li><p class="first">ave/correlate = style name of this fix command</p>
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</li>
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<li><p class="first">Nevery = use input values every this many timesteps</p>
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</li>
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<li><p class="first">Nrepeat = # of correlation time windows to accumulate</p>
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</li>
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<li><p class="first">Nfreq = calculate time window averages every this many timesteps</p>
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</li>
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<li><p class="first">one or more input values can be listed</p>
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</li>
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<li><p class="first">value = c_ID, c_ID[N], f_ID, f_ID[N], v_name</p>
|
|
<pre class="literal-block">
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|
c_ID = global scalar calculated by a compute with ID
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c_ID[I] = Ith component of global vector calculated by a compute with ID, I can include wildcard (see below)
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|
f_ID = global scalar calculated by a fix with ID
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|
f_ID[I] = Ith component of global vector calculated by a fix with ID, I can include wildcard (see below)
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|
v_name = global value calculated by an equal-style variable with name
|
|
v_name[I] = Ith component of a vector-style variable with name
|
|
</pre>
|
|
</li>
|
|
<li><p class="first">zero or more keyword/arg pairs may be appended</p>
|
|
</li>
|
|
<li><p class="first">keyword = <em>type</em> or <em>ave</em> or <em>start</em> or <em>prefactor</em> or <em>file</em> or <em>overwrite</em> or <em>title1</em> or <em>title2</em> or <em>title3</em></p>
|
|
<pre class="literal-block">
|
|
<em>type</em> arg = <em>auto</em> or <em>upper</em> or <em>lower</em> or <em>auto/upper</em> or <em>auto/lower</em> or <em>full</em>
|
|
auto = correlate each value with itself
|
|
upper = correlate each value with each succeeding value
|
|
lower = correlate each value with each preceding value
|
|
auto/upper = auto + upper
|
|
auto/lower = auto + lower
|
|
full = correlate each value with every other value, including itself = auto + upper + lower
|
|
<em>ave</em> args = <em>one</em> or <em>running</em>
|
|
one = zero the correlation accumulation every Nfreq steps
|
|
running = accumulate correlations continuously
|
|
<em>start</em> args = Nstart
|
|
Nstart = start accumulating correlations on this timestep
|
|
<em>prefactor</em> args = value
|
|
value = prefactor to scale all the correlation data by
|
|
<em>file</em> arg = filename
|
|
filename = name of file to output correlation data to
|
|
<em>overwrite</em> arg = none = overwrite output file with only latest output
|
|
<em>title1</em> arg = string
|
|
string = text to print as 1st line of output file
|
|
<em>title2</em> arg = string
|
|
string = text to print as 2nd line of output file
|
|
<em>title3</em> arg = string
|
|
string = text to print as 3rd line of output file
|
|
</pre>
|
|
</li>
|
|
</ul>
|
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</div>
|
|
<div class="section" id="examples">
|
|
<h2>Examples</h2>
|
|
<pre class="literal-block">
|
|
fix 1 all ave/correlate 5 100 1000 c_myTemp file temp.correlate
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|
fix 1 all ave/correlate 1 50 10000 &
|
|
c_thermo_press[1] c_thermo_press[2] c_thermo_press[3] &
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|
type upper ave running title1 "My correlation data"
|
|
</pre>
|
|
<p>fix 1 all ave/correlate 1 50 10000 c_thermo_press[*]</p>
|
|
</div>
|
|
<div class="section" id="description">
|
|
<h2>Description</h2>
|
|
<p>Use one or more global scalar values as inputs every few timesteps,
|
|
calculate time correlations bewteen them at varying time intervals,
|
|
and average the correlation data over longer timescales. The
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|
resulting correlation values can be time integrated by
|
|
<a class="reference internal" href="variable.html"><span class="doc">variables</span></a> or used by other <a class="reference internal" href="Section_howto.html#howto-15"><span class="std std-ref">output commands</span></a> such as <a class="reference internal" href="thermo_style.html"><span class="doc">thermo_style custom</span></a>, and can also be written to a file. See the
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|
<a class="reference internal" href="fix_ave_correlate_long.html"><span class="doc">fix ave/correlate/long</span></a> command for an
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|
alternate method for computing correlation functions efficiently over
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very long time windows.</p>
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|
<p>The group specified with this command is ignored. However, note that
|
|
specified values may represent calculations performed by computes and
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|
fixes which store their own “group” definitions.</p>
|
|
<p>Each listed value can be the result of a <a class="reference internal" href="compute.html"><span class="doc">compute</span></a> or
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|
<a class="reference internal" href="fix.html"><span class="doc">fix</span></a> or the evaluation of an equal-style or vector-style
|
|
<a class="reference internal" href="variable.html"><span class="doc">variable</span></a>. In each case, the compute, fix, or variable
|
|
must produce a global quantity, not a per-atom or local quantity. If
|
|
you wish to spatial- or time-average or histogram per-atom quantities
|
|
from a compute, fix, or variable, then see the <a class="reference internal" href="fix_ave_chunk.html"><span class="doc">fix ave/chunk</span></a>, <a class="reference internal" href="fix_ave_atom.html"><span class="doc">fix ave/atom</span></a>, or
|
|
<a class="reference internal" href="fix_ave_histo.html"><span class="doc">fix ave/histo</span></a> commands. If you wish to convert a
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|
per-atom quantity into a single global value, see the <a class="reference internal" href="compute_reduce.html"><span class="doc">compute reduce</span></a> command.</p>
|
|
<p>The input values must either be all scalars. What kinds of
|
|
correlations between input values are calculated is determined by the
|
|
<em>type</em> keyword as discussed below.</p>
|
|
<p><a class="reference internal" href="compute.html"><span class="doc">Computes</span></a> that produce global quantities are those which
|
|
do not have the word <em>atom</em> in their style name. Only a few
|
|
<a class="reference internal" href="fix.html"><span class="doc">fixes</span></a> produce global quantities. See the doc pages for
|
|
individual fixes for info on which ones produce such values.
|
|
<a class="reference internal" href="variable.html"><span class="doc">Variables</span></a> of style <em>equal</em> and <em>vector</em> are the only
|
|
ones that can be used with this fix. Variables of style <em>atom</em> cannot
|
|
be used, since they produce per-atom values.</p>
|
|
<p>Note that for values from a compute or fix, the bracketed index I can
|
|
be specified using a wildcard asterisk with the index to effectively
|
|
specify multiple values. This takes the form “*” or “*n” or “n*” or
|
|
“m*n”. If N = the size of the vector (for <em>mode</em> = scalar) or the
|
|
number of columns in the array (for <em>mode</em> = vector), then an asterisk
|
|
with no numeric values means all indices from 1 to N. A leading
|
|
asterisk means all indices from 1 to n (inclusive). A trailing
|
|
asterisk means all indices from n to N (inclusive). A middle asterisk
|
|
means all indices from m to n (inclusive).</p>
|
|
<p>Using a wildcard is the same as if the individual elements of the
|
|
vector had been listed one by one. E.g. these 2 fix ave/correlate
|
|
commands are equivalent, since the <a class="reference internal" href="compute_pressure.html"><span class="doc">compute pressure</span></a> command creates a global vector with 6
|
|
values.</p>
|
|
<pre class="literal-block">
|
|
compute myPress all pressure NULL
|
|
fix 1 all ave/correlate 1 50 10000 c_myPress[*]
|
|
fix 1 all ave/correlate 1 50 10000 &
|
|
c_myPress[1] c_myPress[2] c_myPress[3] &
|
|
c_myPress[4] c_myPress[5] c_myPress[6]
|
|
</pre>
|
|
<hr class="docutils" />
|
|
<p>The <em>Nevery</em>, <em>Nrepeat</em>, and <em>Nfreq</em> arguments specify on what
|
|
timesteps the input values will be used to calculate correlation data.
|
|
The input values are sampled every <em>Nevery</em> timesteps. The
|
|
correlation data for the preceding samples is computed on timesteps
|
|
that are a multiple of <em>Nfreq</em>. Consider a set of samples from some
|
|
initial time up to an output timestep. The initial time could be the
|
|
beginning of the simulation or the last output time; see the <em>ave</em>
|
|
keyword for options. For the set of samples, the correlation value
|
|
Cij is calculated as:</p>
|
|
<pre class="literal-block">
|
|
Cij(delta) = ave(Vi(t)*Vj(t+delta))
|
|
</pre>
|
|
<p>which is the correlation value between input values Vi and Vj,
|
|
separated by time delta. Note that the second value Vj in the pair is
|
|
always the one sampled at the later time. The ave() represents an
|
|
average over every pair of samples in the set that are separated by
|
|
time delta. The maximum delta used is of size (<em>Nrepeat</em>-1)*<em>Nevery</em>.
|
|
Thus the correlation between a pair of input values yields <em>Nrepeat</em>
|
|
correlation datums:</p>
|
|
<pre class="literal-block">
|
|
Cij(0), Cij(Nevery), Cij(2*Nevery), ..., Cij((Nrepeat-1)*Nevery)
|
|
</pre>
|
|
<p>For example, if Nevery=5, Nrepeat=6, and Nfreq=100, then values on
|
|
timesteps 0,5,10,15,...,100 will be used to compute the final averages
|
|
on timestep 100. Six averages will be computed: Cij(0), Cij(5),
|
|
Cij(10), Cij(15), Cij(20), and Cij(25). Cij(10) on timestep 100 will
|
|
be the average of 19 samples, namely Vi(0)*Vj(10), Vi(5)*Vj(15),
|
|
Vi(10)*V j20), Vi(15)*Vj(25), ..., Vi(85)*Vj(95), Vi(90)*Vj(100).</p>
|
|
<p><em>Nfreq</em> must be a multiple of <em>Nevery</em>; <em>Nevery</em> and <em>Nrepeat</em> must be
|
|
non-zero. Also, if the <em>ave</em> keyword is set to <em>one</em> which is the
|
|
default, then <em>Nfreq</em> >= (<em>Nrepeat</em>-1)*<em>Nevery</em> is required.</p>
|
|
<hr class="docutils" />
|
|
<p>If a value begins with “c_”, a compute ID must follow which has been
|
|
previously defined in the input script. If no bracketed term is
|
|
appended, the global scalar calculated by the compute is used. If a
|
|
bracketed term is appended, the Ith element of the global vector
|
|
calculated by the compute is used. See the discussion above for how I
|
|
can be specified with a wildcard asterisk to effectively specify
|
|
multiple values.</p>
|
|
<p>Note that there is a <a class="reference internal" href="compute_reduce.html"><span class="doc">compute reduce</span></a> command
|
|
which can sum per-atom quantities into a global scalar or vector which
|
|
can thus be accessed by fix ave/correlate. Or it can be a compute
|
|
defined not in your input script, but by <a class="reference internal" href="thermo_style.html"><span class="doc">thermodynamic output</span></a> or other fixes such as <a class="reference internal" href="fix_nh.html"><span class="doc">fix nvt</span></a>
|
|
or <a class="reference internal" href="fix_temp_rescale.html"><span class="doc">fix temp/rescale</span></a>. See the doc pages for
|
|
these commands which give the IDs of these computes. Users can also
|
|
write code for their own compute styles and <a class="reference internal" href="Section_modify.html"><span class="doc">add them to LAMMPS</span></a>.</p>
|
|
<p>If a value begins with “f_”, a fix ID must follow which has been
|
|
previously defined in the input script. If no bracketed term is
|
|
appended, the global scalar calculated by the fix is used. If a
|
|
bracketed term is appended, the Ith element of the global vector
|
|
calculated by the fix is used. See the discussion above for how I can
|
|
be specified with a wildcard asterisk to effectively specify multiple
|
|
values.</p>
|
|
<p>Note that some fixes only produce their values on certain timesteps,
|
|
which must be compatible with <em>Nevery</em>, else an error will result.
|
|
Users can also write code for their own fix styles and <a class="reference internal" href="Section_modify.html"><span class="doc">add them to LAMMPS</span></a>.</p>
|
|
<p>If a value begins with “v_”, a variable name must follow which has
|
|
been previously defined in the input script. Only equal-style or
|
|
vector-style variables can be referenced; the latter requires a
|
|
bracketed term to specify the Ith element of the vector calculated by
|
|
the variable. See the <a class="reference internal" href="variable.html"><span class="doc">variable</span></a> command for details.
|
|
Note that variables of style <em>equal</em> or <em>vector</em> define a formula
|
|
which can reference individual atom properties or thermodynamic
|
|
keywords, or they can invoke other computes, fixes, or variables when
|
|
they are evaluated, so this is a very general means of specifying
|
|
quantities to time correlate.</p>
|
|
<hr class="docutils" />
|
|
<p>Additional optional keywords also affect the operation of this fix.</p>
|
|
<p>The <em>type</em> keyword determines which pairs of input values are
|
|
correlated with each other. For N input values Vi, for i = 1 to N,
|
|
let the number of pairs = Npair. Note that the second value in the
|
|
pair Vi(t)*Vj(t+delta) is always the one sampled at the later time.</p>
|
|
<ul class="simple">
|
|
<li>If <em>type</em> is set to <em>auto</em> then each input value is correlated with
|
|
itself. I.e. Cii = Vi*Vi, for i = 1 to N, so Npair = N.</li>
|
|
<li>If <em>type</em> is set
|
|
to <em>upper</em> then each input value is correlated with every succeeding
|
|
value. I.e. Cij = Vi*Vj, for i < j, so Npair = N*(N-1)/2.</li>
|
|
<li>If <em>type</em> is set
|
|
to <em>lower</em> then each input value is correlated with every preceeding
|
|
value. I.e. Cij = Vi*Vj, for i > j, so Npair = N*(N-1)/2.</li>
|
|
<li>If <em>type</em> is set to <em>auto/upper</em> then each input value is correlated
|
|
with itself and every succeeding value. I.e. Cij = Vi*Vj, for i >= j,
|
|
so Npair = N*(N+1)/2.</li>
|
|
<li>If <em>type</em> is set to <em>auto/lower</em> then each input value is correlated
|
|
with itself and every preceding value. I.e. Cij = Vi*Vj, for i <= j,
|
|
so Npair = N*(N+1)/2.</li>
|
|
<li>If <em>type</em> is set to <em>full</em> then each input value is correlated with
|
|
itself and every other value. I.e. Cij = Vi*Vj, for i,j = 1,N so
|
|
Npair = N^2.</li>
|
|
</ul>
|
|
<p>The <em>ave</em> keyword determines what happens to the accumulation of
|
|
correlation samples every <em>Nfreq</em> timesteps. If the <em>ave</em> setting is
|
|
<em>one</em>, then the accumulation is restarted or zeroed every <em>Nfreq</em>
|
|
timesteps. Thus the outputs on successive <em>Nfreq</em> timesteps are
|
|
essentially independent of each other. The exception is that the
|
|
Cij(0) = Vi(T)*Vj(T) value at a timestep T, where T is a multiple of
|
|
<em>Nfreq</em>, contributes to the correlation output both at time T and at
|
|
time T+Nfreq.</p>
|
|
<p>If the <em>ave</em> setting is <em>running</em>, then the accumulation is never
|
|
zeroed. Thus the output of correlation data at any timestep is the
|
|
average over samples accumulated every <em>Nevery</em> steps since the fix
|
|
was defined. it can only be restarted by deleting the fix via the
|
|
<a class="reference internal" href="unfix.html"><span class="doc">unfix</span></a> command, or by re-defining the fix by re-specifying
|
|
it.</p>
|
|
<p>The <em>start</em> keyword specifies what timestep the accumulation of
|
|
correlation samples will begin on. The default is step 0. Setting it
|
|
to a larger value can avoid adding non-equilibrated data to the
|
|
correlation averages.</p>
|
|
<p>The <em>prefactor</em> keyword specifies a constant which will be used as a
|
|
multiplier on the correlation data after it is averaged. It is
|
|
effectively a scale factor on Vi*Vj, which can be used to account for
|
|
the size of the time window or other unit conversions.</p>
|
|
<p>The <em>file</em> keyword allows a filename to be specified. Every <em>Nfreq</em>
|
|
steps, an array of correlation data is written to the file. The
|
|
number of rows is <em>Nrepeat</em>, as described above. The number of
|
|
columns is the Npair+2, also as described above. Thus the file ends
|
|
up to be a series of these array sections.</p>
|
|
<p>The <em>overwrite</em> keyword will continuously overwrite the output file
|
|
with the latest output, so that it only contains one timestep worth of
|
|
output. This option can only be used with the <em>ave running</em> setting.</p>
|
|
<p>The <em>title1</em> and <em>title2</em> and <em>title3</em> keywords allow specification of
|
|
the strings that will be printed as the first 3 lines of the output
|
|
file, assuming the <em>file</em> keyword was used. LAMMPS uses default
|
|
values for each of these, so they do not need to be specified.</p>
|
|
<p>By default, these header lines are as follows:</p>
|
|
<pre class="literal-block">
|
|
# Time-correlated data for fix ID
|
|
# TimeStep Number-of-time-windows
|
|
# Index TimeDelta Ncount valueI*valueJ valueI*valueJ ...
|
|
</pre>
|
|
<p>In the first line, ID is replaced with the fix-ID. The second line
|
|
describes the two values that are printed at the first of each section
|
|
of output. In the third line the value pairs are replaced with the
|
|
appropriate fields from the fix ave/correlate command.</p>
|
|
<hr class="docutils" />
|
|
<p>Let Sij = a set of time correlation data for input values I and J,
|
|
namely the <em>Nrepeat</em> values:</p>
|
|
<pre class="literal-block">
|
|
Sij = Cij(0), Cij(Nevery), Cij(2*Nevery), ..., Cij(*Nrepeat-1)*Nevery)
|
|
</pre>
|
|
<p>As explained below, these datums are output as one column of a global
|
|
array, which is effectively the correlation matrix.</p>
|
|
<p>The <em>trap</em> function defined for <a class="reference internal" href="variable.html"><span class="doc">equal-style variables</span></a>
|
|
can be used to perform a time integration of this vector of datums,
|
|
using a trapezoidal rule. This is useful for calculating various
|
|
quantities which can be derived from time correlation data. If a
|
|
normalization factor is needed for the time integration, it can be
|
|
included in the variable formula or via the <em>prefactor</em> keyword.</p>
|
|
<hr class="docutils" />
|
|
<p><strong>Restart, fix_modify, output, run start/stop, minimize info:</strong></p>
|
|
<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 a global array of values which can be accessed by
|
|
various <a class="reference internal" href="Section_howto.html#howto-15"><span class="std std-ref">output commands</span></a>. The values can
|
|
only be accessed on timesteps that are multiples of <em>Nfreq</em> since that
|
|
is when averaging is performed. The global array has # of rows =
|
|
<em>Nrepeat</em> and # of columns = Npair+2. The first column has the time
|
|
delta (in timesteps) between the pairs of input values used to
|
|
calculate the correlation, as described above. The 2nd column has the
|
|
number of samples contributing to the correlation average, as
|
|
described above. The remaining Npair columns are for I,J pairs of the
|
|
N input values, as determined by the <em>type</em> keyword, as described
|
|
above.</p>
|
|
<ul class="simple">
|
|
<li>For <em>type</em> = <em>auto</em>, the Npair = N columns are ordered: C11, C22, ...,
|
|
CNN.</li>
|
|
<li>For <em>type</em> = <em>upper</em>, the Npair = N*(N-1)/2 columns are ordered: C12,
|
|
C13, ..., C1N, C23, ..., C2N, C34, ..., CN-1N.</li>
|
|
<li>For <em>type</em> = <em>lower</em>, the Npair = N*(N-1)/2 columns are ordered: C21,
|
|
C31, C32, C41, C42, C43, ..., CN1, CN2, ..., CNN-1.</li>
|
|
<li>For <em>type</em> = <em>auto/upper</em>, the Npair = N*(N+1)/2 columns are ordered:
|
|
C11, C12, C13, ..., C1N, C22, C23, ..., C2N, C33, C34, ..., CN-1N,
|
|
CNN.</li>
|
|
<li>For <em>type</em> = <em>auto/lower</em>, the Npair = N*(N+1)/2 columns are ordered:
|
|
C11, C21, C22, C31, C32, C33, C41, ..., C44, CN1, CN2, ..., CNN-1,
|
|
CNN.</li>
|
|
<li>For <em>type</em> = <em>full</em>, the Npair = N^2 columns are ordered: C11, C12,
|
|
..., C1N, C21, C22, ..., C2N, C31, ..., C3N, ..., CN1, ..., CNN-1,
|
|
CNN.</li>
|
|
</ul>
|
|
<p>The array values calculated by this fix are treated as intensive. If
|
|
you need to divide them by the number of atoms, you must do this in a
|
|
later processing step, e.g. when using them in a
|
|
<a class="reference internal" href="variable.html"><span class="doc">variable</span></a>.</p>
|
|
<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>
|
|
</div>
|
|
<div class="section" id="restrictions">
|
|
<h2>Restrictions</h2>
|
|
<blockquote>
|
|
<div>none</div></blockquote>
|
|
</div>
|
|
<div class="section" id="related-commands">
|
|
<h2>Related commands</h2>
|
|
<p><a class="reference internal" href="fix_ave_correlate_long.html"><span class="doc">fix ave/correlate/long</span></a>,
|
|
<a class="reference internal" href="compute.html"><span class="doc">compute</span></a>, <a class="reference internal" href="fix_ave_time.html"><span class="doc">fix ave/time</span></a>, <a class="reference internal" href="fix_ave_atom.html"><span class="doc">fix ave/atom</span></a>, <a class="reference internal" href="fix_ave_chunk.html"><span class="doc">fix ave/chunk</span></a>,
|
|
<a class="reference internal" href="fix_ave_histo.html"><span class="doc">fix ave/histo</span></a>, <a class="reference internal" href="variable.html"><span class="doc">variable</span></a></p>
|
|
<p><strong>Default:</strong> none</p>
|
|
<p>The option defaults are ave = one, type = auto, start = 0, no file
|
|
output, title 1,2,3 = strings as described above, and prefactor = 1.0.</p>
|
|
</div>
|
|
</div>
|
|
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|
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</div>
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</div>
|
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<footer>
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<div class="rst-footer-buttons" role="navigation" aria-label="footer navigation">
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<a href="fix_ave_correlate_long.html" class="btn btn-neutral float-right" title="fix ave/correlate/long command" accesskey="n">Next <span class="fa fa-arrow-circle-right"></span></a>
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<a href="fix_ave_chunk.html" class="btn btn-neutral" title="fix ave/chunk command" accesskey="p"><span class="fa fa-arrow-circle-left"></span> Previous</a>
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</div>
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<hr/>
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<div role="contentinfo">
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<p>
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© Copyright 2013 Sandia Corporation.
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</p>
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