[Pw_forum] metal optimization tricks and constraining in slab

[David Foster]

Hi,

I have emailed this message two times former (Thu Apr 10 19:46:20 CEST 2014 and Fri Apr 11 
16:05:26 CEST 2014) but I didn't received them in my mail box, so, I think it has not been sent
to any member. 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