Subject: RE: G92/MP4 Problem

From: [email-masked] (Eugene Fleischmann)
Date: Mon, 16 May 94 18:12:02 EDT

To: [email-masked]
Subject: Re: CCL:G92 problem

> From [email-masked] Mon May 16 14:16 EDT 1994
> To: [email-masked]
> Subject: CCL:G92 problem
> 
> Hi Netters,
> I'm having a problem with G92 mounted on a RISC/6000/590 machine.  I am
> attempting to run an MP4SDTQ single point using MO's 15 to 196 for correlation.
> The default setup is MaxDisk=250000000 and SCF=Direct (the disk is set to the
> maximum of our physical disk).  The problem occurs after completion of the
> SCF energy with messages
>    Semi-Direct transformation.
> Usinging 298129326 words of disk,even though MaxDisk= 250000000
> ModeAB=          2 MOrb=          18  LenV=    11379966
> LaSXX=    50679171LtotXX=  50679171LenRXX=50679171
> LTotAB=   51502527 MaxLAS=  84032676  LenRXY=84032676
> NonZer=  101358342 LenScr= 163417479  LnRSAI=         0
> LnScr1=          0 MaxDsk= 250000000Total=  298129326
> File extend in NtrExt1 failed.
> File extend in NtrExt1 failed. Invalid argument
> 
> Several questions:  Why did Gaussian try to allocate beyond the maximum
> disk size?
> Why did the calculation change to semi-direct?
> Can anyone suggest a workaround other than "punting" or trying to obtain
> 'off-site' computer time?
> Thanks for any help.
> Pat Plummer
> Physplmp@MIZZOU1
> 

Prof. Plummer,

> Several questions:  Why did Gaussian try to allocate beyond the maximum
> disk size?

The amount of disk storage is determined by the number of integrals involving
three virtual orbitals, regardless of MAXDISK.

> Why did the calculation change to semi-direct?

According to the G92 User's Guide, p. 93, the default for the higher
correlated methods is the semi-direct algorithm.  The SCF part of the
calculation may still be performed using the direct algorithm, however,
once the SCF wavefunction has been calculated the MP4 calculation needs
to transform the AO integrals to the MO basis.  If you used "direct" in
the SCF, you have to recalculate the AO integrals as needed and transform
a portion to the MO basis (semi-direct transformation), or generate the
full set of MO integrals (TRAN=FULL), which requires considerable more
disk space.

> Can anyone suggest a workaround other than "punting" or trying to obtain
> 'off-site' computer time?

You could send me the input deck via e-mail, and I will calculate your
single-point energy for you on one of our C90 systems.  A system having
104 basis functions required only 760 CPU seconds; since yours is twice
as large (roughly) I would guess that it would take four times as long,
yet still less than one hour.

Gene

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
	Eugene D. Fleischmann, Ph.D.
	Computational Chemist
	Cray Research, Inc.		(609) 252-1250
	121 Commons Way			[email-masked]
	Princeton, NJ  08540
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