[Pw_forum] metal optimization tricks and constraining in slab

[Paolo Giannozzi]

On Fri, 2014-04-11 at 09:36 -0700, David Foster wrote:

> I have emailed this message two times former (...) but 
> I didn't received them in my mail box, so, I think it 
> has not been sent to any member. 

think twice ... I received both

P.

> I repeat it again, and sorry for inconvenience.
> 
> 
>  
> 
> Dear Users and supporters
> 
> "....Thank you for your quick answers...."
> 
> I have two questions:
> 
> 1- I prepared 3*3*3 bulk Pd super-cell, and used "vc-relax". The relaxation needed
> 
>    more than 200 iteration. I finally relaxed it with restarting command. Please help
>    
>    me in setting following parameters for fast relaxation for metals:
>    
>    a- degauss (I think increasing it helps for fast coarse optimization, but after it
>    
>       needs more fine optimization.
>       with increasing it, does it need more "nbnd"?)
> 
>    b-mixing beta ( in my calculation, I set it to 0.3, but I got very fluctuation in optimization.
> 
>      does increasing it helps optimization speed?)
> 
>   c- I prepared input by a program that saves the structure in cif format. I used the coordination
> 
>      with "crystal" card. is it true?
> 
> 2- I prepared 5 layers Pd slab and should fix two layers' coordination, but I don't know how.
>     I read input style help but confused.
> 
> Thanks again
> 
> 
> 
> 
> Regards
> 
> David Foster
> 
> Ph.D. Student of Chemistry
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-- 
Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222