[Pw_forum] variable-cell optimizations

[Paolo Giannozzi]

On Tuesday 03 January 2006 23:35, Nichols A. Romero wrote:

> How does PWSCF handle the number of planewaves during a variable-cell
> optimizations? Are the planewaves or energy cutoff kept constant?

the energy cutoff is kept constant

> Does it use the method of Bernasconi et. al Phys. Chem. Solids, 56 501
> (1995)?

I don't know about the specific reference ("J. Phys. Chem. Solids", by the
way) but I think so. It uses a modified functional in which the kinetic 
energy (the electronic one appearing in the Kohn-Sham equations) is 
calculated by replacing (k+G)^2 with 
(k+G)^2 + qcutz * (1 + erf( ((k+G)^2 - ecfixed ) / q2sigma ) ) . 

P.

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Paolo Giannozzi             e-mail:  giannozz at nest.sns.it
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