Subject: Dmol efficiency: frosen core & basis sets

From: "Ivan I. Oleinik" <[email-masked]>
Date: Tue, 7 Jul 1998 14:07:36 +0100 (BST)

Hello all,

I am trying to tune MSI DMol3 to get maximum efficiency in calculations of
the large systems, containing H, C, Si, Ge. The obvious choice would be to
reduce atomic basis set to the necessary minimum (especially for Si and
Ge). There was an option in previus version of Dmol 96.0/4.0.0 to use
frozen core approximation to remove core orbitals from SCF procedure.

Does anybody know are there any ways to use frozen core approximation in
the new version DMol3. An attempt to use "basis" keyword with the flags to
froze the core, eg

Basis                   user
                        6   7 1 0 0 2 0 2 2

for carbon  results in  error message;

too many wave functions, val, core 1 16 1 0
Leave Status         13

Another question in this connection. Is there a possibility to assign the
different basis sets to atoms of the same element but located at different
parts of the system. 

Any other comments on increasing efficiency of DMol calculations (with
primary concern with geometry optimisation, not energetics) would be very
welome. 

Ivan Oleinik.

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Dr. Ivan I. Oleinik             E-mail : [email-masked]
Department of Materials
University of Oxford
Parks Road
Oxford OX1 3PH                     Tel : +44 (0)1865 283325
United Kingdom                     Fax : +44 (0)1865 273764 
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