[Pw_forum] PWscf and highly parallel machines

[Nichols A. Romero]

Didn't even realize what I had typed. That is what happens when you are
running from
one place to the next :^)

Thanks to Paolo for explaining things more eloquently.

On 2/15/07, Paolo Giannozzi <giannozz at nest.sns.it> wrote:
>
>
> On Feb 15, 2007, at 16:37 , Nichols A. Romero wrote:
>
> > There are two ways to solve for the KS ground state.
> > 1. Direct minimization of KS functional
> > 2. Self-consistently solving the KS eqn.
> >
> > The conjugate-gradient (cg) in PWSCF and CP are not doing
> > different things same thing.
>
> let me say something different the same thing :-)
>
> 'cg' in PWscf: *self-consistency + fixed-potential diagonalization*
> The diagonalization is performed by transforming the secular
> problem into a minimum problem (nothing really fancy:
> min <\psi|H\psi> + orthogonality) and solving for each band
> in sequence, using conjugate gradient. Slower than Davidson
> diagonalization, uses less memory. To be used in case of trouble
> with Davidson or if memory is tight.
>
> 'cg' in CP: conjugate-gradient algorithm for minimization of the
> *energy functional* (global minimization).
>
> Paolo
> ---
> Paolo Giannozzi, Democritos and University of Udine, Italy
>
>
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>



-- 
Nichols A. Romero, Ph.D.
1613 Denise Dr. Apt. D
Forest Hill, MD 21050
443-567-8328 (C)
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