[Pw_forum] questions about vc-relax or geomtry optimization

[jideson]

Dear Dr. Axel,
Thank you for your response quickly. 
Can you give me some details about BFGS  in geometry optimization(which
is used in CASTEP) ?  I choose it in pwscf , it complains not
implement. 
I want  to predict  a structure using pwscf . Can I get a reasonable
result  using vc-relax when  my configure is  far from equilibrium.

 

在 2007-08-19日的 20:44 -0400，Axel Kohlmeyer写道： 
> 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> _______________________________________________
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> J> Pw_forum at pwscf.org
> J> http://www.democritos.it/mailman/listinfo/pw_forum
> J> 

-- 
Best regards

Jideson