Posted by Per Åke Malmqvist on October 14, 2005 at 10:05:29:
In Reply to: Dipole moments posted by Siva on October 12, 2005 at 11:42:00:
: Sir:
: We are interested in studying the dipole moments of excited states in order to understand certain spectroscopic shifts. It is clear from the caspt2 output file, that the 1-st cartesian moments refer to these dipole moments. Our query concerns the convention by with the components are given: do they give the center of positive charge relative to the center of negative charge or is it the other way round?
The cartesian moments in atomic units are computed using a negative unit charge of the
electron. Ex: For a LiF molecule with the Li end pointing in the z axis direction, the
z-component of the cartesian 1st moment is positive. Thus it is identical to the dipole
moment. The dipole moments are also given in Debye units.
Please note that the default operation of the caspt2 program is to compute properties
as an approximate expectation value.