Folks,
The manual says not to do it unless you know what you're doing, and since I
don't, I thought I'd ask...
I want to calculate the adsorption energy of an ion (let's say OH- ) on a metal
surface (let's call it M, denoting a neutral slab of a few layers). The
straight-forward calculation would be
dE = E(MOH-) - (E(M) + E(OH-))
Ideally all in the same size of unit cell. There is the problem of BSSE, but I
understand that and know more or less how to handle it. My question concerns the
two charged calculations (MOH- and OH-) and the effect the background charge
that will compensate for the excess electron has on the energy. Is this change
in the Hamiltonian big enough to make the calculated dE meaningless? I have seen
cases where dE (after correction for BSSE, including relaxation energy) came out
positive, which seemed chemically unlikely.
Thanks in advance,
Herbert
--
Herbert Fruchtl
Senior Scientific Computing Officer
School of Chemistry, School of Mathematics and Statistics
University of St Andrews
--
The University of St Andrews is a charity registered in Scotland:
No SC013532
