"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)

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angle_style charmm 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)"_#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.

[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#2_3 section for more info on packages.

[Related commands:]

"angle_coeff"_angle_coeff.html

[Default:] none

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