[Pw_forum] relax

Axel Kohlmeyer akohlmey at cmm.chem.upenn.edu
Sun Nov 30 12:56:45 CET 2008

On 11/30/08, wangqj1 <wangqj1 at 126.com> wrote:
>  Dear all

dear wang,

>       When relax ,which algorithm is better ? Bfgs or damp ? I use bfgs,but

the better algorithm is the one that works better for your system.
there is no "golden" algorithm that is always the best. sometimes
even algorithms considered the worst can be the best choice.
please note, that many algorithms have adjustable parameters
that can make all the difference. to begin with, you first have to
define what is "best" (fastest convergence, not getting stuck in local
minima easily, efficient handling of shallow or highly  asymmetric
potential surfaces).

...and on top of that, it is quite likely that a combination of algorithms
(i.e. start with one that "gets you down" fast, and then switching to
one that can find a minimum fast) would be the "best" solution for
many scenarios.

> find it very slow . Anybody who know about this ,please give some advice

you'll have to define "slow" as well. you always have to see this
in relation to the problem you are studying...


> ,thank you .
> Q J Wang
> XiangTan University

Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
  Center for Molecular Modeling   --   University of Pennsylvania
Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
If you make something idiot-proof, the universe creates a better idiot.

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