"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c

:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Commands_all.html)

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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.

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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 on the "Speed packages"_Speed_packages.html doc
page.  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 "Build
package"_Build_package.html doc page 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"_Run_options.html when you invoke LAMMPS, or you can use the
"suffix"_suffix.html command in your input script.

See "Speed packages"_Speed_packages.html doc page for more
instructions on how to use the accelerated styles effectively.

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[Restrictions:]

This angle style can only be used if LAMMPS was built with the
MOLECULE package.  See the "Build package"_Build_package.html doc page
for more info.

[Related commands:]

"angle_coeff"_angle_coeff.html

[Default:] none

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:link(angle-MacKerell)
[(MacKerell)] MacKerell, Bashford, Bellott, Dunbrack, Evanseck, Field,
Fischer, Gao, Guo, Ha, et al, J Phys Chem, 102, 3586 (1998).
