[Pw_forum] vc-relax calculation

[David Foster]

Dear Elham
For adsorption process, you should follow steps:

1- vc-relax your experimental primitive or conventional cell.

2-cleave your surface by miller indexes, and construct your slab. you must provide 15-20 A vacuum
in z-direction.

3- only relax the slab with constrain in z and angles (alpha, beta, gamma).
if you vc-relax the slab, then your z-direction lattice constant will change.
if you model surface, then you must fix position of some 3-5 first layers as a bulk.
if you model thin film, then you can relax all atoms, even low layers.

4- take frequencies to be sure that your slab is in local minimum.

5- add you adsorbant on the surface, and repeat steps 3 and 4.

for DOS and BAND you need exact scf and high-k point, respectively.



Regards

David Foster

Ph.D. Student of Chemistry

--------------------------------------------
On Mon, 8/3/15, Elham <e.chemistry83 at gmail.com> wrote:

 Subject: Re: [Pw_forum] vc-relax calculation
 To: pw_forum at pwscf.org
 Date: Monday, August 3, 2015, 5:45 AM
 
 Dear David
 Thank
 you very much for  answer my question.
 
 First I vc-relax the
 pure surface (obtain a b c) and then different molecules adsorb on surface do
 vc-relax (a b c) a slightly changed.
 for
 comparison result It is
 problem? Best
 RegardsElhamPh.D. Student of
 Chemistry
 
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