[CPMD-list] failure to optimize the wavefunction with KPOINTS MONKHORST-PACK

[Axel Kohlmeyer]

On Tue, 22 Feb 2005, Wolfgang Fritsch wrote:

WF> Dear CPMD experts,

dear wolfgang,

WF> in preparation of a band structure calculation I am trying to optimize 
WF> the wavefunction and also to determine the density. I find that the entry
WF> 
WF> KPOINTS MONKHORST-PACK
WF> 
WF> leads to the failure to optimize the wavefunction. Without this entry in 

using the KPOINTS keyword will lead to the use of a totally different
subroutine for performing the conjugate gradient algorithm (and 
using a complex instead of a real wavefunction, IIRC). the k-points
version are not that well tested. does it work with lanczos?
also: you may want to try out the FREE ENERGY FUNCTIONAL option,
since you compound may be metallic (or close enough).

WF> the SYSTEM section, the wavefunction is optimized as usual by finding 
WF> the minimum energy. With this entry - which in my understanding should 
WF> not affect the energy - the energy appears to approach a minimum but 
WF> turns around towards higher energies, see step 351 in the attached 
WF> output. It resumes lowering the energy in step 385 in the output but 
WF> doesn't seems to converge to the minimum energy.
WF> 
WF> I wonder what I am missing here. I apologize beforehand just in case I 
WF> goofed in any way.

no problem. the k-points part in cpmd is not so well tested,
and generally not so much in use, so it is quite likely, that
there are more bugs in it there.

regards,
	axel.

WF> Yours,
WF> 
WF> Wolfgang
WF> 
WF> Input
WF> =====================================================================

-- 

=======================================================================
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/
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If you make something idiot-proof, the universe creates a better idiot.