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fix wiggle command

Syntax:

fix ID group-ID wiggle dim amplitude period

Examples:

fix 1 frozen wiggle 3.0 0.5 

Description:

Move a group of atoms in a sinusoidal oscillation. This is useful in granular simulations when boundary atoms are wiggled to induce packing of the dynamic atoms. The dimension dim of movement is specified as is the amplitude and period of the oscillations. Each timestep the dim coordinate of each atom is set to

coord = coord0 + A - A cos (omega * delta) 

where coord0 is the coordinate at the time the fix was specified, A is the amplitude, omega is 2 PI / period, and delta is the elapsed time since the fix was specified. The velocity of the atom is set to the derivative of this expression.

Restrictions: none

Related commands: none

Default: none