[CPMD-list] Problems defining ending times etc.

[Axel Kohlmeyer]

>>> "MH" == Michael Hawlitzky <hawlitzk at uni-mainz.de> writes:

MH> Dear Mr. Kohlmeyer,

MH> Thanks a lot for your hint!
MH> You are right, the wavefunctions aren't converged correctly.
MH> I was also wondering why the iteration takes so many steps (more than 600
MH> without gemax getting significantly below 1e-04), but most probably
MH> this comes from the position data which I have taken from a classical
MH> MD run.

that is exactly my impression, too. the wavefunction seems to converge
properly only when your ionic positions are close to the equilibrium.
although i have found that in some cases, e.g. bulk water, the classical
md optimized positions are very close to the QM optimum and the
wavefunction converges very good. 

you should be able to improve the situation by running a few short
mds of a few hundred steps and then reoptimize the wavefunction with
a tighter convergence until you have a 'stable' md. alternatively,
you could run a geometry optimization first (i found using LBFGS with 
adaptive convergence to be very efficient, there are some examples
for useful parameter combinations in the mailing list archives).

good luck,
        axel kohlmeyer.

MH> Greetings,
MH> Michael

MH> -- 
MH> Dipl.-Math. Michael Hawlitzky
MH> Institut für Physik, Universität Mainz
MH> Staudingerweg 9, Raum 01-517
MH> 55099 Mainz
MH> Tel.: (+49)6131-3925158
MH> Fax:  (+49)6131-3925441

MH> _______________________________________________
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--

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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.