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
|
|
|
|
:link(lws,http://lammps.sandia.gov)
|
|
:link(ld,Manual.html)
|
|
:link(lc,Section_commands.html#comm)
|
|
|
|
:line
|
|
|
|
angle_style cosine/periodic command :h3
|
|
angle_style cosine/periodic/omp command :h3
|
|
|
|
[Syntax:]
|
|
|
|
angle_style cosine/periodic :pre
|
|
|
|
[Examples:]
|
|
|
|
angle_style cosine/periodic
|
|
angle_coeff * 75.0 1 6 :pre
|
|
|
|
[Description:]
|
|
|
|
The {cosine/periodic} angle style uses the following potential, which
|
|
is commonly used in the "DREIDING"_Section_howto.html#howto_4 force
|
|
field, particularly for organometallic systems where {n} = 4 might be
|
|
used for an octahedral complex and {n} = 3 might be used for a
|
|
trigonal center:
|
|
|
|
:c,image(Eqs/angle_cosine_periodic.jpg)
|
|
|
|
where C, B and n are coefficients defined for each angle type.
|
|
|
|
See "(Mayo)"_#Mayo for a description of the DREIDING force field
|
|
|
|
The following coefficients must be defined for each angle type via the
|
|
"angle_coeff"_angle_coeff.html command as in the example above, or in
|
|
the data file or restart files read by the "read_data"_read_data.html
|
|
or "read_restart"_read_restart.html commands:
|
|
|
|
C (energy)
|
|
B = 1 or -1
|
|
n = 1, 2, 3, 4, 5 or 6 for periodicity :ul
|
|
|
|
Note that the prefactor C is specified and not the overall force
|
|
constant K = C / n^2. When B = 1, it leads to a minimum for the
|
|
linear geometry. When B = -1, it leads to a maximum for the linear
|
|
geometry.
|
|
|
|
:line
|
|
|
|
Styles with a {cuda}, {gpu}, {intel}, {kk}, {omp}, or {opt} suffix are
|
|
functionally the same as the corresponding style without the suffix.
|
|
They have been optimized to run faster, depending on your available
|
|
hardware, as discussed in "Section_accelerate"_Section_accelerate.html
|
|
of the manual. The accelerated styles take the same arguments and
|
|
should produce the same results, except for round-off and precision
|
|
issues.
|
|
|
|
These accelerated styles are part of the USER-CUDA, GPU, USER-INTEL,
|
|
KOKKOS, USER-OMP and OPT packages, respectively. They are only
|
|
enabled if LAMMPS was built with those packages. See the "Making
|
|
LAMMPS"_Section_start.html#start_3 section for more info.
|
|
|
|
You can specify the accelerated styles explicitly in your input script
|
|
by including their suffix, or you can use the "-suffix command-line
|
|
switch"_Section_start.html#start_7 when you invoke LAMMPS, or you can
|
|
use the "suffix"_suffix.html command in your input script.
|
|
|
|
See "Section_accelerate"_Section_accelerate.html of the manual for
|
|
more instructions on how to use the accelerated styles effectively.
|
|
|
|
:line
|
|
|
|
[Restrictions:]
|
|
|
|
This angle style can only be used if LAMMPS was built with the
|
|
MOLECULAR package (which it is by default). See the "Making
|
|
LAMMPS"_Section_start.html#start_3 section for more info on packages.
|
|
|
|
[Related commands:]
|
|
|
|
"angle_coeff"_angle_coeff.html
|
|
|
|
[Default:] none
|
|
|
|
:line
|
|
|
|
:link(Mayo)
|
|
[(Mayo)] Mayo, Olfason, Goddard III, J Phys Chem, 94, 8897-8909
|
|
(1990).
|