Dear John,

I was involved in its implementation, and have been using it regularly
on molecules
of different sizes, from small to relatively large;
the largest molecule I treated was at least of the order of 60 atoms
using the
all-electron TZP basis, and I may have tried also a system of around
100 atoms;
the SCF part is really fast, but afterwards it needs to calculate exact
exchange
which may take a long time;
and depending if you're running in parallel or not, it may take indeed
some days;
just hang in there, and let it finish...

NOTE:
always use the all-electron basis when using the HFEXCHANGE keyword !!

On Wednesday, June 1, 2005, at 09:35 PM, john mcgrady wrote:

> Does anyone have experience of using the metagga and hfexchange keys
> for large molecules?
> The newsletter (March 2004) refers to the 'feasibility of using this
> option for up to 50 atoms'. I would like to apply it to a rather
> larger system (80 atoms), but have been stuck at 'SCF converged' for 2
> days (vs <1 hour to converge the SCF). Is a calculation of this size
> feasible but just very long, or am I wasting my time?
> Thanks for any guidance.
>
> John McGrady
>
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dr. Marcel Swart

Theoretische Chemie
Vrije Universiteit Amsterdam
Faculteit der Exacte Wetenschappen

De Boelelaan 1083
1081 HV Amsterdam
The Netherlands

Tel +31-20-5987619
Fax +31-20-5987629
E-mail m.swart_at_few.vu.nl
Web http://www.few.vu.nl/~swart
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Received on 2005-06-01 21:50:47