3.6. Compute styles

Classes that compute scalar and vector quantities like temperature and the pressure tensor, as well as classes that compute per-atom quantities like kinetic energy and the centro-symmetry parameter are derived from the Compute class. New styles can be created to add new calculations to LAMMPS.

Compute_temp.cpp is a simple example of computing a scalar temperature. Compute_ke_atom.cpp is a simple example of computing per-atom kinetic energy.

Here is a brief description of methods you define in your new derived class. See compute.h for details.

init

perform one time setup (required)

init_list

neighbor list setup, if needed (optional)

compute_scalar

compute a scalar quantity (optional)

compute_vector

compute a vector of quantities (optional)

compute_peratom

compute one or more quantities per atom (optional)

compute_local

compute one or more quantities per processor (optional)

pack_comm

pack a buffer with items to communicate (optional)

unpack_comm

unpack the buffer (optional)

pack_reverse

pack a buffer with items to reverse communicate (optional)

unpack_reverse

unpack the buffer (optional)

remove_bias

remove velocity bias from one atom (optional)

remove_bias_all

remove velocity bias from all atoms in group (optional)

restore_bias

restore velocity bias for one atom after remove_bias (optional)

restore_bias_all

same as before, but for all atoms in group (optional)

pair_tally_callback

callback function for tally-style computes (optional).

memory_usage

tally memory usage (optional)

Tally-style computes are a special case, as their computation is done in two stages: the callback function is registered with the pair style and then called from the Pair::ev_tally() function, which is called for each pair after force and energy has been computed for this pair. Then the tallied values are retrieved with the standard compute_scalar or compute_vector or compute_peratom methods. The compute styles in the USER-TALLY package provide examples for utilizing this mechanism.