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lammps/doc/src/angle_charmm.txt
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"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 charmm command :h3
angle_style charmm/intel command :h3
angle_style charmm/kk command :h3
angle_style charmm/omp command :h3
[Syntax:]
angle_style charmm :pre
[Examples:]
angle_style charmm
angle_coeff 1 300.0 107.0 50.0 3.0 :pre
[Description:]
The {charmm} angle style uses the potential
:c,image(Eqs/angle_charmm.jpg)
with an additional Urey_Bradley term based on the distance {r} between
the 1st and 3rd atoms in the angle. K, theta0, Kub, and Rub are
coefficients defined for each angle type.
See "(MacKerell)"_#angle-MacKerell for a description of the CHARMM 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:
K (energy/radian^2)
theta0 (degrees)
K_ub (energy/distance^2)
r_ub (distance) :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 {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 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
MOLECULE 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(angle-MacKerell)
[(MacKerell)] MacKerell, Bashford, Bellott, Dunbrack, Evanseck, Field,
Fischer, Gao, Guo, Ha, et al, J Phys Chem, 102, 3586 (1998).
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