[molpro-user] Hard limits on CAS space sizes?

[Dr Seth OLSEN]

Hi Molpro-users,

The machine I am running on (Sun v880) is a 64 bit machine, and I have compiled molpro with 64 bit integers.  Attempting to run the job with a CAS(18,16) active space yields the same result.

Could this be related to another parameter, set perhaps in molpro.rc?

Cheers,

Seth

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Dr Seth Olsen, PhD
Postdoctoral Fellow, Computational Systems Biology 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 

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----- Original Message -----
From: Alex Brown <alex.brown at ualberta.ca>
Date: Tuesday, May 24, 2005 11:48 am
Subject: Re: [molpro-user] Hard limits on CAS space sizes?

> Hi Seth,
> 
> > I'm doing CASSCF on a molecule with 274 contracted basis 
> functions and 
> > 126 electrons.  I would like to perform a CAS(18,18) calculation 
> on 
> > this molecule, averaged over the two lowest states.  I'm working 
> on an 
> > SMP box with 8 processors and 30GB of ram.  So far I have not had 
> much 
> > luck with the calculation, which quits very soon after calling 
> MULTI, 
> > before the calculation apparently starts in earnest.  Am I 
> running 
> > into a hard-coded limit in molpro?  If so, can I recompile and 
> get 
> > around the limit?
> 
>   This came up on the list a while ago. The hard limit is 16 
> active 
> orbitals on a 32-bit system. If you have a 64-bit machine, then 
> this 
> should not be the problem. Below I quote Peter Knowles response to 
> the 
> list - there were a couple other posts/responses to this thread at 
> that 
> time.
> 
> I hope this helps.
> 
> Regards,
> Alex
> 	
> Alex Brown
> Assistant Professor
> Department of Chemistry
> University of Alberta
> Edmonton, AB
> T6G 2G2
> http://www.chem.ualberta.ca/~abrown/
> 
> 
> 
> 
> • 	To: The Matt <thompsma at xxxxxxxxxxxx>
> 	• 	Subject: Too Many Active Orbitals?
> 	• 	From: Peter Knowles <P.J.Knowles at xxxxxxxxxx>
> 	• 	Date: Wed, 02 Jul 2003 17:45:41 +0100
> 	• 	Cc: Molpro List <molpro-user at xxxxxxxxxx>
> 	• 	In-reply-to: <1057163627.537.6.camel at ixion.colorado.edu>
> 	• 	References: <1057163627.537.6.camel at ixion.colorado.edu>
> 	• 	Sender: owner-molpro-user at xxxxxxxxxxxxxxxxx
> 	• 	User-agent: X-Mailer: Wanderlust/2.11.0
> Yes, the number of closed+active (mrci, rs2) or active (mcscf, rs2c)
> orbitals can be at most half of the number of bits in an integer
> (integers are used to store patterns with 2 bits per active
> orbital). Apologies that this is not clearly stated in the manual.
> 
> Peter
> >
> >
> > The error I get reads:
> >  ERROR EXIT
> >  CURRENT STACK:      MAIN
> >
> >  Which is not very descriptive.  I appear to have plenty of 
> scratch 
> > space, but this would not appear to be the problem anyway b/c I 
> get 
> > the same error running direct.  I note that the error is not your 
> > usual 'not enough memory error' either.  This makes me think that 
> > there may be a deeper issue.  Am I correct in this?  Is this 
> > calculation out of reach?
> >
> > Cheers,
> >
> > Seth
> >
> >
> >
> >
> > ccmsccmsccmsccmsccmsccmsccmsccmsccmsccmsccmsccmsccmsccmsccmsccms
> >
> > Dr Seth Olsen, PhD
> > Postdoctoral Fellow, Computational Systems Biology 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
> >
> > ccmsccmsccmsccmsccmsccmsccmsccmsccmsccmsccmsccmsccmsccmsccmsccms
> >
> >
> >
> >
> >
>