[CPMD-list] Non-physical aqueous Na+ behavior

[Axel Kohlmeyer]

On Wed, 22 Jun 2005, Dave Sherman wrote:

DS> Dear CPMD list,
DS> 
[...]

DS> pathology with the Na+ pseudopotential going on? (I'm using the 
DS> Vanderbilt group Na potential with Ceperly-Alder exchange and semicore 
DS> sp states..).  Is it possible that, when the Na+ cations get close 

dave, 

i suggest you better don't submit this to science. it seems
you are a victim of a 'feature' in the uspp reader in CPMD.

to be compatible with CPMD, uspps have to have the same number of
projectors per angular momentum and must not skip over any angular
momentum. the potential you are mentioning, has two projectors for
the s- and p-channel but only one for the d-channel and thus
the potential will give unphysical results. sorry.

DS> enough, each Na+ sees the psuedopotential of the other and gets bound 
DS> to it?   I believe I'm still on the Born-Oppenheimer surface;  Ekinc is 
DS> pretty stable at 0.15 AU and EHAM is very stable  (to within 0.001 AU). 
DS>   I'm using CPMD 3.7.

ok, is there a reason for still sticking with cpmd 3.7?
the uspp reader in the current CPMD version is able to 
detect (most?) incompatible vanderbilt potentials. so
you should really update (and get a large number of other
improvements to boot).

in case you cannot update, i'm attaching a patch containing
a backport of a few IMO essential _and_ backportable fixes
to the CPMD 3.7 branch (including the test in the uspp reader).

best regards,
	axel.

DS> Thanks for your help!
DS> 
DS> Dave Sherman
DS> 
DS> David M. Sherman
DS> Professor of Geochemistry
DS> Department of Earth Sciences
DS> University of Bristol
DS> Bristol BS8 1RJ UNITED KINGDOM
DS> Phone: 44-(0)117-954-5446
DS> http://mineral.gly.bris.ac.uk
DS> 
DS> _______________________________________________
DS> CPMD-list mailing list
DS> CPMD-list at cpmd.org
DS> http://cpmd.org/mailman/listinfo/cpmd-list
DS> 
DS> 

-- 

=======================================================================
Dr. Axel Kohlmeyer   e-mail: axel.kohlmeyer at theochem.ruhr-uni-bochum.de
Lehrstuhl fuer Theoretische Chemie          Phone: ++49 (0)234/32-26673
Ruhr-Universitaet Bochum - NC 03/53         Fax:   ++49 (0)234/32-14045
D-44780 Bochum  http://www.theochem.ruhr-uni-bochum.de/~axel.kohlmeyer/
=======================================================================
If you make something idiot-proof, the universe creates a better idiot.
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