## Calculating partial charges for interatomic coulombic interactions

I want to understand how to compute (or find a database for) partial charges, which I can then apply to calculating coulombic interactions.

From here, it is said that electronegativity is related to the partial charge by a quadratic function, but it seems to not be fully explained.

How would I compute partial charges? Ultimately, I want to calculate interactions for all pairs between Si,Fe,Mg, Ca, and O, or at least between O and these cations.