[molpro-user] DFT-SAPT shifts

[Andreas Hesselmann]

The shifts are determined as

eig(HOMO)-(-I.P.)

and are usually positive for LDA/GGA's.

An example: the Ne atom has the experimental
I.P. of 0.793 hartree while e.g. the PBE0 functional
gives a HOMO energy of about -0.589 hartree.
So the shift of the bulk potential to be
used in the input is 0.204 (value in a.u.).
Note that this correction accounts for the
derivative discontinuity that is absent in
LDA and GGA's.

At the end of the KS calculation using the 
asymptotic correction the HOMO energy should 
be close to the (negative) experimental I.P.
that was used to determine the shift value.

You may also use vertical I.P.'s from ab-initio
or DFT calculations. This is particularly helpful in
cases where no experimental I.P.'s are available.

Wishes,
Andreas




On Tuesday 04 August 2009 09:13, ERSIN YURTSEVER wrote:
> Hi
>
> In DFT-SAPT,
>
> is  the shift defined as d=Experimental IP-(-Energy of HOMO) or is it the
> other way around?
>
> Is the unit of the shift hatree or eV?
>
> thanks
>
> _______________________________________________
> Molpro-user mailing list
> Molpro-user at molpro.net
> http://www.molpro.net/mailman/listinfo/molpro-user

-- 
--------------------------------------------------
Andreas Hesselmann
Institut für Physikalische und Theoretische Chemie
Universität Erlangen
Egerlandstraße 3
91058 Erlangen / Germany
Phone:  +49 9131/85-25021
E-Mail: andreas.hesselmann at chemie.uni-erlangen.de
-------------------------------------------------