forked from lijiext/lammps
79 lines
2.4 KiB
Plaintext
79 lines
2.4 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 quartic command :h3
|
|
angle_style quartic/omp command :h3
|
|
|
|
[Syntax:]
|
|
|
|
angle_style quartic :pre
|
|
|
|
[Examples:]
|
|
|
|
angle_style quartic
|
|
angle_coeff 1 129.1948 56.8726 -25.9442 -14.2221 :pre
|
|
|
|
[Description:]
|
|
|
|
The {quartic} angle style uses the potential
|
|
|
|
:c,image(Eqs/angle_quartic.jpg)
|
|
|
|
where theta0 is the equilibrium value of the angle, and K is a
|
|
prefactor. Note that the usual 1/2 factor is included in K.
|
|
|
|
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:
|
|
|
|
theta0 (degrees)
|
|
K2 (energy/radian^2)
|
|
K3 (energy/radian^3)
|
|
K4 (energy/radian^4) :ul
|
|
|
|
Theta0 is specified in degrees, but LAMMPS converts it to radians
|
|
internally; hence the units of K are in energy/radian^2.
|
|
|
|
: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
|
|
USER_MISC package. See the "Making LAMMPS"_Section_start.html#start_3
|
|
section for more info on packages.
|
|
|
|
[Related commands:]
|
|
|
|
"angle_coeff"_angle_coeff.html
|
|
|
|
[Default:] none
|