[molpro-user] Active orbitals limit

Dr Seth OLSEN s.olsen1 at uq.edu.au
Tue Jul 26 02:50:46 BST 2005

Hi Xinzheng,

The only way to get beyond it is to move to a 64 bit computer
architecture, as far as I know.  Because of the way molpro represents
the configurations, the number of active orbitals is equal to the
bitsize of integers on your machine divided by two.  

There is more on this in the mailing list archive.




Dr Seth Olsen, PhD
Postdoctoral Fellow, Biomolecular Modeling Group
Centre for Computational Molecular Science
Chemistry Building,
The University of Queensland
Qld 4072, Brisbane, Australia

tel (617) 33653732
fax (617) 33654623
email: s.olsen1 at uq.edu.au
Web: www.ccms.uq.edu.au 


----- Original Message -----
From: Xinzheng Yang <yangxinzheng at gmail.com>
Date: Tuesday, July 26, 2005 5:04 am
Subject: [molpro-user] Active orbitals limit
> Dear Molpro user,
> Why the number of active orbitals in CASSCF calculation are limited 
> to 16?
> Is there any special point for this limitation? Is there any way to
> increase this
> limitation?
> Thanks a lot!
> -- 
> Xinzheng Yang
> 1071 Clayton Ln, Apt. 1406
> Austin, TX 78723

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