forked from lijiext/lammps
70 lines
2.4 KiB
Plaintext
70 lines
2.4 KiB
Plaintext
"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
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:link(lws,http://lammps.sandia.gov)
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:link(ld,Manual.html)
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:link(lc,Section_commands.html#comm)
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:line
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fix rdf command :h3
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[Syntax:]
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fix ID group-ID rdf N file Nbin itype1 jtype1 itype2 jtype2 ... :pre
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ID, group-ID are documented in "fix"_fix.html command
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rdf = style name of this fix command
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N = compute radial distribution function (RDF) every this many timesteps
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file = filename to write radial distribution function info to
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Nbin = number of RDF bins
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itypeN = central atom type for RDF pair N
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jtypeN = distribution atom type for RDF pair N :ul
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[Examples:]
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fix 1 all rdf 500 rdf.out 100 1 1
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fix 1 fluid rdf 10000 rdf.out 100 1 1 1 2 2 1 2 2 :pre
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[Description:]
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Compute the radial distribution function (RDF), also known as g(r),
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and coordination number every N steps. The RDF for each specified
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atom type pair is histogrammed in Nbin bins from distance 0 to Rc,
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where Rc = the maximum force cutoff for any pair of atom types. An
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atom pair only contributes to the RDF if
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both atoms are in the fix group
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the distance between them is within the maximum force cutoff
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their interaction is stored in the neighbor list :ul
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Bonded atoms (1-2, 1-3, 1-4 interactions within a molecular topology)
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with a pairwise weighting factor of 0.0 are not included in the RDF;
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pairs with a non-zero weighting factor are included. The weighting
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factor is set by the "special_bonds"_special_bonds.html command.
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The RDF statistics for each timestep are written to the specified
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file, as are the RDF values averaged over all timesteps.
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[Restart, fix_modify, output, run start/stop, minimize info:]
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No information about this fix is written to "binary restart
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files"_restart.html. None of the "fix_modify"_fix_modify.html options
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are relevant to this fix. No global scalar or vector or per-atom
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quantities are stored by this fix for access by various "output
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commands"_Section_howto.html#4_15. No parameter of this fix can be
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used with the {start/stop} keywords of the "run"_run.html command.
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This fix is not invoked during "energy minimization"_minimize.html.
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[Restrictions:]
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The RDF is not computed for distances longer than the force cutoff,
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since processors (in parallel) don't know atom coordinates for atoms
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further away than that distance. If you want an RDF for larger {r},
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you'll need to post-process a dump file.
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[Related commands:]
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"pair_style"_pair_style.html
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[Default:] none
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