forked from lijiext/lammps
89 lines
4.0 KiB
HTML
89 lines
4.0 KiB
HTML
<HTML>
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<CENTER><A HREF = "http://lammps.sandia.gov">LAMMPS WWW Site</A> - <A HREF = "Manual.html">LAMMPS Documentation</A> - <A HREF = "Section_commands.html#comm">LAMMPS Commands</A>
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<HR>
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<H3>compute command
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</H3>
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<P><B>Syntax:</B>
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</P>
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<PRE>compute ID group-ID style args
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</PRE>
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<UL><LI>ID = user-assigned name for the computation
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<LI>group-ID = ID of the group of atoms to perform the computation on
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<LI>style = one of a list of possible style names (see below)
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<LI>args = arguments used by a particular style
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</UL>
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<P><B>Examples:</B>
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</P>
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<PRE>compute 1 all temp
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compute newtemp flow temp/partial 1 1 0
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compute 3 all ke/atom
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</PRE>
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<P><B>Description:</B>
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</P>
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<P>Create a computation that will be performed on a group of atoms.
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</P>
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<P>In LAMMPS, a "compute" is used in several ways. Computes that
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calculate one or more values for the entire group of atoms can output
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those values via the <A HREF = "thermo_style.html">thermo_style custom</A> or <A HREF = "fix_ave_time.html">fix
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ave/time</A> command. Or the values can be referenced
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in a <A HREF = "variable.html">variable equal</A> command. Computes that calculate
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a temperature or pressure are used by fixes that do thermostatting or
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barostatting and when atom velocities are created. Computes that
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calculate one or more values for each atom in the group can output
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those values via the <A HREF = "dump.html">dump custom</A> command or the <A HREF = "fix_ave_spatial.html">fix
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ave/spatial</A> command.
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</P>
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<P>LAMMPS creates its own computes for thermodynamic output and dumping
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atom snapshots. Likewise fixes that compute temperature or pressure
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create their own computes. These are discussed in the documentation
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for <A HREF = "thermo_style.html">thermo_style</A>, <A HREF = "dump.html">dump custom</A>, and
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specific <A HREF = "fix.html">fix</A> commands.
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</P>
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<P>In all these cases, the default computes can be replaced by computes
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defined in the input script, as described by the
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<A HREF = "thermo_modify.html">thermo_modify</A> and <A HREF = "fix_modify.html">fix modify</A>
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commands. Code for new computes can also be added to LAMMPS (see
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<A HREF = "Section_modify.html">this section</A> of the manaul) and their
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calculations accessed in the various ways described above.
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</P>
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<P>Properties of a compute can be modified via the
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<A HREF = "compute_modify.html">compute_modify</A> command.
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</P>
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<P>Compute can be deleted with the <A HREF = "uncompute.html">uncompute</A> command.
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</P>
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<P>Each compute style has its own doc page which describes its arguments
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and what it does. Here is an alphabetic list of compute styles
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defined in LAMMPS:
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</P>
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<UL><LI><A HREF = "compute_centro_atom.html">centro/atom</A> - centro-symmetry parameter for each atom
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<LI><A HREF = "compute_epair_atom.html">epair/atom</A> - pairwise energy for each atom
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<LI><A HREF = "compute_etotal_atom.html">etotal/atom</A> - total energy (ke + epair) for each atom
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<LI><A HREF = "compute_ke_atom.html">ke/atom</A> - kinetic energy for each atom
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<LI><A HREF = "compute_pressure.html">pressure</A> - total pressure and pressure tensor
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<LI><A HREF = "compute_rotate_dipole.html">rotate/dipole</A> - rotational energy of dipolar atoms
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<LI><A HREF = "compute_rotate_gran.html">rotate/gran</A> - rotational energy of granular atoms
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<LI><A HREF = "compute_stress_atom.html">stress/atom</A> - stress tensor for each atom
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<LI><A HREF = "compute_temp.html">temp</A> - temperature of group of atoms
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<LI><A HREF = "compute_temp_partial.html">temp/partial</A> - temperature excluding one or more dimensions of velocity
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<LI><A HREF = "compute_temp_ramp.html">temp/ramp</A> - temperature after subtracting a ramped velocity component
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<LI><A HREF = "compute_temp_region.html">temp/region</A> - temperature of a region of atoms
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<LI><A HREF = "compute_variable_atom.html">variable/atom</A> - calculate a formula for each atom
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</UL>
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<P><B>Restrictions:</B> none
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</P>
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<P><B>Related commands:</B>
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</P>
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<P><A HREF = "uncompute.html">uncompute</A>, <A HREF = "compute_modify.html">compute_modify</A>
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</P>
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<P><B>Default:</B> none
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</P>
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</HTML>
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