[molpro-user] memory/disc space requirement for L-CCSD(T)

[Jörg Saßmannshausen]

Dear Ersin,

thanks for the info, I will give it a try and see how it goes.

I take it, all I have to do is
DF-lccsd(t)
instead of
lccsd(t)
or? 
Does it change the energy (much)? 

All the best

Jörg

On Thursday 20 August 2009 09:44:23 you wrote:
> dear Jörg
>
> do you want to try density fitting?. I belive it would solve your
> scratch disk problem.
>
>
> ersin
>
> >>> Jörg Saßmannshausen <jorg.sassmannshausen at strath.ac.uk> 19.08.2009
>
> 17:06 >>>
> Dear all,
>
> having successfully tackled the problem with the not converging SCF, I
> am
> facing a new challenge.
>
> In order to make sure that my molecule of 53 atoms is running smoothly
> on the
> computational node (Quad core Opteron, 12 GB ram, 4 cores), I decided
> to give
> the whole process arouhd 11 GB of RAM, so the OS has got some RAM as
> well.
> However, it was eating up 470 GB of scratch space which is basically
> all I
> could (somehow, and please don't ask how I done it) utilise for that
> calculation. Unfortunately, that was not enough. So, the question is,
> is
> there any way to get these figures (scratch mainly) down to something
> more
> managable?
> From this line:
>  Integral-direct triples not yet available
> I understood that I cannot use direct SCF in oder to save disc space.
>
> Enclosed are the relevant parts of the input file but the coordinates.
>
> memory,350,m    !11 GB of total memory, 2.75 per core
> SET,CHARGE=1    !charge of the molecule is +1
> geomtyp=xyz
> geometry
>    53
> CCSD(T)/cc-pVTZ//mp2/6-31g*
> [ ... ]
> end
>
> hf,maxit=300
> hf,direct
> basis=cc-pVTZ           !cc-pVTZ basis set for all elements
> hf                      !Perform HF calculation
> lccsd(t)                !Perform L-CCSD(T) calculation
>
> The organic molecule contains F, N, O and Si as heteroatoms.
>
> Would somebody mind to point me in the right direction?
>
> All the best from Glasgow!
>
> Jörg
>
> --
> *************************************************************
> Jörg Saßmannshausen
> Research Fellow
> University of Strathclyde
> Department of Pure and Applied Chemistry
> 295 Cathedral St.
> Glasgow
> G1 1XL
>
> email: jorg.sassmannshausen at strath.ac.uk
> web: http://sassy.formativ.net
>
> Please avoid sending me Word or PowerPoint attachments.
> See http://www.gnu.org/philosophy/no-word-attachments.html
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-- 
*************************************************************
Jörg Saßmannshausen
Research Fellow
University of Strathclyde
Department of Pure and Applied Chemistry
295 Cathedral St.
Glasgow
G1 1XL

email: jorg.sassmannshausen at strath.ac.uk
web: http://sassy.formativ.net

Please avoid sending me Word or PowerPoint attachments.
See http://www.gnu.org/philosophy/no-word-attachments.html