[Pw_forum] questions about vc-relax or geomtry optimization

[Axel Kohlmeyer]

On Mon, 20 Aug 2007, jideson wrote:

J> Dear experts,

dear jideson,

J>      I read some  emails about vc-relax in this list, but  still have
J> some questions.  It seems that  geometry optimization (both cell and
J> atomic postions) in pwscf is a diffcult job than other softwares such as

i disagree. it is not difficult, you just need to know what you are
doing and particularly know what you can expect. the quantum espresso
package allows you a lot of flexibility, but the price for that is
that not everything works automatically right. usually, if something
is not working easily, it is an indication, that you have not yet
understood what you are doing (or else it would be obvious) or
you have a problem that is not easy to start with or (which is rare)
have found a bug in the code.

J> CASTEP.  Can you give me a step-by-step tutorial ?

there are some input examples within the distribution
and you may want to check out material from previous QE
tutorials, e.g., the material at:
http://www.vlab.msi.umn.edu/events/lecture.shtml

J>    By the way , another question , are there differences between cp.x
J> and cpmd(www.cpmd.org) code ?  Thanks!   

yes. both have the same origin, there have evolved into 
quite different species by now. 

cheers,
   axel.

J> 
J>  
J> 
J> Best regards
J> 
J> Jideson
J> 
J> _______________________________________________
J> Pw_forum mailing list
J> Pw_forum at pwscf.org
J> http://www.democritos.it/mailman/listinfo/pw_forum
J> 

-- 
=======================================================================
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.