Too Many Active Orbitals?

Peter Knowles P.J.Knowles at
Wed Jul 2 17:45:41 BST 2003

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. 


At 02 Jul 2003 10:33:47 -0600,
Matt Thompson wrote:
> [1  <text/plain (quoted-printable)>]
> I hope this isn't a FAQ, but I couldn't find the answer anywhere.  I am
> trying to do a calculation that has succeeded before on 2002.3, but now
> fails on 2002.6.  The job stops with:
> I tracked this to src/mrci/ciinit.f, but I'm not sure on how to increase
> this.  Is it one of those options in the configure process, or do I need
> to hack a common?  If the hack, is it safe to do?  Or is it a 32-bit
> limit (see below)?
> I am also puzzled why this job did work on .3 and not .6.  Could this be
> due to .6 being on a 32-bit system (dual Xeon with 4 GB of memory) and
> the .3 on a 64-bit system (Alpha with 768 MB)?  If so, are there other
> parameters I need to watch out for that kill on 32-bit?
> Thanks for any help,
> Matt Thompson
> -- 
> "And isn't sanity really just a one-trick pony, anyway?  I mean,
> all you get is one trick, rational thinking, but when you're good
> and crazy, ooh ooh ooh, the sky's the limit!" -- The Tick
>   The Matt --
> [2 This is a digitally signed message part <application/pgp-signature (7bit)>]

Prof. Peter J. Knowles              
Email P.J.Knowles at  Phone +44-121-414-7472  Fax +44-121-414-7471
School of Chemical Sciences, University of Birmingham, Birmingham, B15 2TT, UK

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