[Pw_forum] questions about vc-relax or geomtry optimization

[Axel Kohlmeyer]

On Mon, 20 Aug 2007, jideson wrote:

J> Dear Dr. Axel,
J> Thank you for your response quickly. 
J> Can you give me some details about BFGS  in geometry optimization(which
J> is used in CASTEP) ?  I choose it in pwscf , it complains not
J> implement. 

i cannot comment on CASTEP. pw.x just does _exactly_
what one would expect after reading Doc/INPUT_PW!
bfgs is only available for regular geometry optimization.

J> I want  to predict  a structure using pwscf . Can I get a reasonable
J> result  using vc-relax when  my configure is  far from equilibrium.

that depends on what you define as reasonable.
nobody can tell you anything specific unless 
you provide more specific information. variable
cell calculations need for sure more care than
constant volume calculations as there are more
ways to get wrong results.

...and while you're at it. please remember to provide
name and affiliation.

thanks,
   axel.

[...]

-- 
=======================================================================
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
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If you make something idiot-proof, the universe creates a better idiot.