[CPMD-list] WAVEFUNCTION OPTIMIZATION

[Jan-Willem Handgraaf]

On Monday 07 October 2002 16:27, Veronique Van Speybroeck wrote:
> Dear all,
>
> I am studying a system that contains 32 atoms, among which are O, N, P, H,
> and use therefore Vanderbilt pseudopotentials.  I'm doing now the initial
> optimization of the wavefunction.  How many steps are common for the
> initial wavefunction optimization.  I have already done 1500 steps still
> the convergence is not reached.  Is this normal.  The total energy does
> not systematically decrease.  As an illustration I give the TOTAL ENERGY
> quantity for some of the last steps :

In my experience this does not seem normal. I'm studying systems up to 262 
containing Ru, O, N, C and H. The first wavefunction optimization with ODIIS 
is usually converged within 150 steps, although automatic reinitializations 
occur. This is for Trouiller-Martins PPs. Have you checked whether the total 
energy you get is lower than the sum of the Pseudoatom Total Energies, i.e. 
is the system 'bonding'? You can also start with random wavefunctions in 
stead of the atomic wavefunctions with the keyword INITIALIZE WAVEFUNCTION 
RANDOM.

Good luck,

Jan-Willem



-- 
Jan-Willem Handgraaf
Department of Chemical Engineering
University of Amsterdam
Nieuwe Achtergracht 166
1018 WV Amsterdam
The Netherlands

Room: C6.18
Tel: +31-20-5256492
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Email: jwh at science.uva.nl