forked from lijiext/lammps
85 lines
3.2 KiB
Plaintext
85 lines
3.2 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 ave/atom command :h3
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[Syntax:]
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fix ID group-ID ave/atom Nevery Nrepeat Nfreq compute-ID :pre
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ID, group-ID are documented in "fix"_fix.html command
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ave/atom = style name of this fix command
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Nevery = calculate property every this many timesteps
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Nrepeat = # of times to repeat the Nevery calculation before averaging
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Nfreq = timestep frequency at which the average value is calculated
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compute-ID = ID of per-atom compute that performs the calculation :ul
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[Examples:]
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fix 1 all ave/atom 1 100 100 myVx
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fix 1 all ave/atom 10 20 1000 my_epair :pre
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[Description:]
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Calculate one or more time-averaged per-atom quantities every few
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timesteps. The results of this calculation can be spatially averaged
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via the "fix ave/spatial"_fix_ave_spatial.html command or output
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to a file via the "dump custom"_dump.html command.
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The {compute-ID} specifies a "compute"_compute.html which calculates
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the desired property. It must be a per-atom compute (one with the
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word "atom" in its style name) that calculates one or more values for
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each atom, as opposed to a global compute. The compute must be
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previously defined in the input script. Users can also write code for
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their own compute styles and "add them to LAMMPS"_Section_modify.html.
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The {Nevery}, {Nrepeat}, and {Nfreq} arguments specify how the
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property will be time-averaged. The final averaged value(s) are
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computed every {Nfreq} timesteps. The average is over {Nrepeat}
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values, computed in the preceeding portion of the simulation every
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{Nevery} timesteps. Thus if Nevery=2, Nrepeat=6, and Nfreq=100, then
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values on timesteps 90,92,94,96,98,100 will be used to compute the
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final average at timestep 100. Similary for timesteps
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190,192,194,196,198,200 at timestep 200, etc.
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If this fix is referenced by a "dump custom"_dump.html or "fix
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ave/spatial"_fix_ave_spatial.html command, the time-averaged values
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can only be accessed every {Nfreq} timesteps.
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If the compute calculates a single or multiple values per atom, then
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fix ave/atom will also calculate one or multiple time-averaged
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quantities per atom. This makes a difference in how the quantities
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are referenced in a "dump custom"_dump.html command, e.g. c_ID versus
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c_ID\[2\].
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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 quantities are
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stored by this fix for access by various "output
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commands"_Section_howto.html#4_15.
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This fix computes a scalar per-atom quantity or a vector of per-atom
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quantities which can be accessed by the "dump custom"_dump.html or
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"fix ave/spatial"_fix_ave_spatial.html commands, as discussed in "this
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section"_Section_howto.html#4_15.
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No parameter of this fix can be used with the {start/stop} keywords of
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the "run"_run.html command. This fix is not invoked during "energy
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minimization"_minimize.html.
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[Restrictions:] none
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[Related commands:]
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"compute"_compute.html, "fix ave/spatial"_fix_ave_spatial.html, "dump
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custom"_dump.html
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[Default:] none
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