.. index:: angle_style charmm angle_style charmm command ========================== angle_style charmm/intel command ================================ angle_style charmm/kk command ============================= angle_style charmm/omp command ============================== Syntax """""" .. parsed-literal:: angle_style charmm Examples """""""" .. parsed-literal:: angle_style charmm angle_coeff 1 300.0 107.0 50.0 3.0 Description """"""""""" The *charmm* angle style uses the potential .. image:: Eqs/angle_charmm.jpg :align: center 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 :ref:`(MacKerell) ` for a description of the CHARMM force field. The following coefficients must be defined for each angle type via the :doc:`angle_coeff ` command as in the example above, or in the data file or restart files read by the :doc:`read_data ` or :doc:`read_restart ` commands: * K (energy/radian^2) * theta0 (degrees) * K_ub (energy/distance^2) * r_ub (distance) Theta0 is specified in degrees, but LAMMPS converts it to radians internally; hence the units of K are in energy/radian^2. ---------- 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 :doc:`Section_accelerate ` 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 :ref:`Making LAMMPS ` section for more info. You can specify the accelerated styles explicitly in your input script by including their suffix, or you can use the :ref:`-suffix command-line switch ` when you invoke LAMMPS, or you can use the :doc:`suffix ` command in your input script. See :doc:`Section_accelerate ` of the manual for more instructions on how to use the accelerated styles effectively. ---------- Restrictions """""""""""" This angle style can only be used if LAMMPS was built with the MOLECULE package (which it is by default). See the :ref:`Making LAMMPS ` section for more info on packages. Related commands """""""""""""""" :doc:`angle_coeff ` **Default:** none ---------- .. _angle-MacKerell: **(MacKerell)** MacKerell, Bashford, Bellott, Dunbrack, Evanseck, Field, Fischer, Gao, Guo, Ha, et al, J Phys Chem, 102, 3586 (1998). .. _lws: http://lammps.sandia.gov .. _ld: Manual.html .. _lc: Section_commands.html#comm