forked from lijiext/lammps
85 lines
2.6 KiB
Plaintext
85 lines
2.6 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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dihedral_style harmonic command :h3
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dihedral_style harmonic/omp command :h3
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[Syntax:]
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dihedral_style harmonic :pre
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[Examples:]
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dihedral_style harmonic
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dihedral_coeff 1 80.0 1 2 :pre
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[Description:]
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The {harmonic} dihedral style uses the potential
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:c,image(Eqs/dihedral_harmonic.jpg)
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The following coefficients must be defined for each dihedral type via the
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"dihedral_coeff"_dihedral_coeff.html command as in the example above, or in
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the data file or restart files read by the "read_data"_read_data.html
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or "read_restart"_read_restart.html commands:
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K (energy)
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d (+1 or -1)
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n (integer >= 0) :ul
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IMPORTANT NOTE: Here are important points to take note of when
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defining LAMMPS dihedral coefficients for the harmonic style, so that
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they are compatible with how harmonic dihedrals are defined by other
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force fields:
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The LAMMPS convention is that the trans position = 180 degrees, while
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in some force fields trans = 0 degrees. :ulb,l
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Some force fields reverse the sign convention on {d}. :l
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Some force fields let {n} be positive or negative which corresponds to
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{d} = 1 or -1 for the harmonic style. :ule,l
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:line
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Styles with a {cuda}, {gpu}, {intel}, {kk}, {omp}, or {opt} suffix are
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functionally the same as the corresponding style without the suffix.
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They have been optimized to run faster, depending on your available
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hardware, as discussed in "Section_accelerate"_Section_accelerate.html
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of the manual. The accelerated styles take the same arguments and
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should produce the same results, except for round-off and precision
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issues.
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These accelerated styles are part of the USER-CUDA, GPU, USER-INTEL,
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KOKKOS, USER-OMP and OPT packages, respectively. They are only
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enabled if LAMMPS was built with those packages. See the "Making
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LAMMPS"_Section_start.html#start_3 section for more info.
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You can specify the accelerated styles explicitly in your input script
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by including their suffix, or you can use the "-suffix command-line
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switch"_Section_start.html#start_7 when you invoke LAMMPS, or you can
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use the "suffix"_suffix.html command in your input script.
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See "Section_accelerate"_Section_accelerate.html of the manual for
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more instructions on how to use the accelerated styles effectively.
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:line
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[Restrictions:]
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This dihedral style can only be used if LAMMPS was built with the
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MOLECULE package (which it is by default). See the "Making
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LAMMPS"_Section_start.html#start_3 section for more info on packages.
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[Related commands:]
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"dihedral_coeff"_dihedral_coeff.html
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[Default:] none
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