forked from lijiext/lammps
91 lines
2.8 KiB
Plaintext
91 lines
2.8 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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angle_style cosine/periodic command :h3
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angle_style cosine/periodic/omp command :h3
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[Syntax:]
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angle_style cosine/periodic :pre
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[Examples:]
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angle_style cosine/periodic
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angle_coeff * 75.0 1 6 :pre
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[Description:]
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The {cosine/periodic} angle style uses the following potential, which
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is commonly used in the "DREIDING"_Section_howto.html#howto_4 force
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field, particularly for organometallic systems where {n} = 4 might be
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used for an octahedral complex and {n} = 3 might be used for a
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trigonal center:
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:c,image(Eqs/angle_cosine_periodic.jpg)
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where C, B and n are coefficients defined for each angle type.
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See "(Mayo)"_#Mayo for a description of the DREIDING force field
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The following coefficients must be defined for each angle type via the
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"angle_coeff"_angle_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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C (energy)
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B = 1 or -1
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n = 1, 2, 3, 4, 5 or 6 for periodicity :ul
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Note that the prefactor C is specified and not the overall force
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constant K = C / n^2. When B = 1, it leads to a minimum for the
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linear geometry. When B = -1, it leads to a maximum for the linear
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geometry.
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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 angle 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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"angle_coeff"_angle_coeff.html
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[Default:] none
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:line
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:link(Mayo)
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[(Mayo)] Mayo, Olfason, Goddard III, J Phys Chem, 94, 8897-8909
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(1990).
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