Subject: Pair Potentials from ab initio/DFT calcs?

From: Dave Price <[email-masked]>
Date: Fri, 20 Mar 1998 16:40:53 +0000

Dear All,
                I have been trying to derive a set of pair potentails
for some small diatomic molecules
and atoms in a metal oxide lattice using DFT calculations.  The lattice
ion in each case was surrounded
by point charges to represent counter ions and the atom or molecule
placed at distances between
1 and 10 Ang from the ion and the energy of the systems were
calculated.  This has been of questionable
success.  (I know that DFT doesn't describe vdW forces very well, if at
all).

Question 1:  Has anyone else had success with these sort of
calculations?

Question 2: How does one overcome the convergence problems of
intrinsically unstable geometries?

Question 3: Can the problems of the lowering of symmetry by placing say
an atom 10 Ang away from
a ion with cubically arranged point charges cause convergence problems
and be overcome?

Any help would be appreciated.
                    Cheers,
                                    Dave

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Dr. David W. Price,       Tel: +44 (0)118 9875123  extn 7415
Department of Chemistry,  Fax: +44 (0)118 9316331
University of Reading,    mailto:[email-masked]
Whiteknights,
READING                http://www.chem.rdg.ac.uk/g50/mmrg/dave/dave.html
RG6 6AD
U.K.

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