Syntax:
displace_atoms group-ID style args keyword value ...
move args = delx dely delz delx,dely,delz = distance to displace in each dimension (distance units) ramp args = ddim dlo dhi dim clo chi ddim = x or y or z dlo,dhi = displacement distance between dlo and dhi (distance units) dim = x or y or z clo,chi = lower and upper bound of domain to displace (distance units)
keyword = units value = box or lattice
Examples:
displace_atoms top move 0 -5 0 units box displace_atoms flow ramp x 0.0 5.0 y 2.0 20.5
Description:
Displace a group of atoms. This can be useful to move atoms a large distance before beginning a simulation. For example, in a shear simulation, an initial strain can be imposed on the system. Or two groups of atoms can be brought into closer proximity.
The move style displaces the group of atoms by the specified 3d distance. The ramp style displaces atoms a variable amount in one dimension depending on the atom's coordinate in a (possibly) different dimension. For example, the second example command displaces atoms in the x-direction an amount between 0.0 and 5.0 distance units. Each atom's displacement depends on the fractional distance its y coordinate is between 2.0 and 20.5. Atoms with y-coordinates outside those bounds will be moved the minimum (0.0) or maximum (5.0) amount.
Distance units for the displacement are determined by the setting of box or lattice for the units keyword. Box means distance units as defined by the units command - e.g. Angstroms for real units. Lattice means to use lattice spacings as defined by the lattice command. The default is to use lattice units.
Care should be taken not to move atoms on top of other atoms. After the move, atoms are remapped to the periodic simulation box. In parallel, atoms should not be moved so far that they cross more than one processor's sub-domain, else they may be lost. If this is a problem, successive displace_atom commands can be used to move a greater distance.
Restrictions: none
Related commands: none
Default:
The option defaults are units = lattice.