Syntax:
compute ID group-ID property/atom input1 input2 ...
possible attributes = id, mol, type, mass, x, y, z, xs, ys, zs, xu, yu, zu, ix, iy, iz, vx, vy, vz, fx, fy, fz, q, mux, muy, muz, radius, omegax, omegay, omegaz, angmomx, angmomy, angmomz, quatw, quati, quatj, quatk, tqx, tqy, tqz
id = atom ID mol = molecule ID type = atom type mass = atom mass x,y,z = unscaled atom coordinates xs,ys,zs = scaled atom coordinates xu,yu,zu = unwrapped atom coordinates ix,iy,iz = box image that the atom is in vx,vy,vz = atom velocities fx,fy,fz = forces on atoms q = atom charge mux,muy,muz = orientation of dipolar atom radius = radius of extended spherical particle omegax,omegay,omegaz = angular velocity of extended particle angmomx,angmomy,angmomz = angular momentum of extended particle quatw,quati,quatj,quatk = quaternion components for aspherical particles tqx,tqy,tqz = torque on extended particles
Examples:
compute 1 all property/atom xs vx fx mux compute 2 all property/atom type compute 1 all property/atom ix iy iz
Description:
Define a computation that simply stores atom attributes for each atom in the group. This is useful so that the values can be used by other output commands that take computes as inputs. See for example, the compute reduce, fix ave/atom, fix ave/histo, fix ave/spatial, and atom-style variable commands.
The list of possible attributes is the same as that used by the dump custom command, which describes their meaning. Basically, this list gives your input script access to any per-atom quantity stored by LAMMPS.
The values are stored in a per-atom vector or array as discussed below. Zeroes are stored for atoms not in the specified group.
Output info:
This compute calculates a per-atom vector or per-atom array depending on the number of input values. If a single input is specified, a per-atom vector is produced. If two or more inputs are specified, a per-atom array is produced where the number of columns = the number of inputs. The vector or array can be accessed by any command that uses per-atom values from a compute as input. See this section for an overview of LAMMPS output options.
The vector or array values will be in whatever units the corresponding attribute is in, e.g. velocity units for vx, charge units for q, etc.
Restrictions: none
Related commands:
dump custom, compute reduce, fix ave/atom, fix ave/spatial
Default: none