Subject: QUESTION ABOUT COULOMBIC POTENTIAL

From: Patricia Lozano-Casal <P.Lozano-Casal|at|ed.ac.uk>
Date: Tue, 20 Apr 2004 13:37:39 +0100

SUBJECT: QUESTION ABOUT COULOMBIC POTENTIAL

Dear all,

I am trying to write a program to calculate the electrostatic contribution of
the lattice energy for molecular crystals. I have run plane-wave DFT
calculations (using the CASTEP package) to calculate the total lattice energy
and using Mulliken charges I hoped to estimate the electrostatic contribution
by coding a simple Coulombic potential. But, I get really weird results!! I am
overestimating my lattice energy by many orders of magnitude.

I know that Mulliken charges are not the ideal point charge to use for this but
I had not expected my numbers to be that wrong. Could anybody help or if not,
could anybody recommend and existing program to use instead (preferably free)?

Many thanks,

Patricia Lozano-Casal (p.lozano-casal|at|ed.ac.uk)

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