This is part of the vatom module

Calculate the center for a group of atoms, with arbitrary weights.

Examples

Glossary of keywords and components

Description of components

By default this Action calculates the following quantities. These quantities can be referenced elsewhere in the input by using this Action's label followed by a dot and the name of the quantity required from the list below.

Quantity	Description
x	the x coordinate of the virtual atom
y	the y coordinate of the virtual atom
z	the z coordinate of the virtual atom
mass	the mass of the virtual atom
charge	the charge of the virtual atom

The atoms involved can be specified using

ATOMS

the list of atoms which are involved the virtual atom's definition. For more information on how to specify lists of atoms see Groups and Virtual Atoms

Options

NOPBC	( default=off ) ignore the periodic boundary conditions when calculating distances
MASS	( default=off ) If set center is mass weighted
PHASES	( default=off ) Compute center using trigonometric phases
WEIGHTS	Center is computed as a weighted average.
SET_CHARGE	Set the charge of the virtual atom to a given value.
SET_MASS	Set the mass of the virtual atom to a given value.