calulate charge on a vacancy or interstitial

[HIMANI]

I want to calculate charge on the vacancies and interstitial present in our structure.  Please suggest me a way to do it.

[zh]

For a vacancy in a structure, it is meaningful to estimate the charges of atoms next to the vacancy site.  For the charge of atom (host or interstitial atom), it can be obtained by the Mulliken charge population analysis. 

[Umberto Martinez]

Well, charge (one or more electrons) can be trapped into a vacancy site as for the so called  color centers in MgO, for example.

You can add a ghost atom at the center of your vacancy site and calculate the Mulliken population of such configuration.
The Mulliken population of your ghost atom can be an estimate of the amount charge trapped in the vacancy.
Check for a proper basis set for the ghost atom!