# cal

### Syntax

cal group_name cal_variable

• group_name = a string (length <= 30)

• cal_variable = energy or force or stress

### Examples

cal green_cone force
cal small_sphere stress


### Description

This commands calculates certain quantities associated with new groups and/or restart groups. The group_name must match that of one of these groups.

energy is the total potential energy in a group divided by the total number of nodes and atoms in the group. It is a scalar.

force and stress are the total force and stress in a group, respectively. force is a $3\times 1$ vector while stress is a $3\times 3$ tensor.

Results of this command are written to group_cal_# with a frequency of reduce_freq, where # is the ID of calculation. For stress, a $3\times 3$ strain tensor of the simulation box is appended right after the stress tensor.

There cannot be fewer cal commands than cal_number, which should not be larger than new_group_number + restart_group_number. When there are more cal commands in cac.in than cal_number, those appearing later will be ignored.

calculation.f90 and group_cal.f90

None.