[Pw_forum] Au (111) Surface Energy

Jack Davis JXD231 at bham.ac.uk
Mon Nov 18 15:30:20 CET 2013


Dear Ari,

Any other papers you can provide relating to this problem would be extremely useful. Thank you very much.

Best Wishes,
Jack Davis

On 15 Nov 2013, at 21:18, Ari P Seitsonen <Ari.P.Seitsonen at iki.fi> wrote:


Dear Jack Davis,

 It is well known in the community that this is not a very accurate approach to calculate the surface energy, even if in principle correct (or, even the definition): You should at least make sure that the bulk is calculated along the (111) direction with the same k point sampling. Only if you are very well converged with the k point sampling in both the slab and bulk you might get a converged value. A classic article discussing this problem is

Vincenzo Fiorentini and M Methfessel 1996 J. Phys.: Condens. Matter 8 6525 doi:10.1088/0953-8984/8/36/005
"Extracting convergent surface energies from slab calculations"

 I can also try to find some more recent references if you wish.

   Greetings from Zurich,

      apsi

-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
 Ari P Seitsonen / Ari.P.Seitsonen at iki.fi<mailto:Ari.P.Seitsonen at iki.fi> / http://www.iki.fi/~apsi/
 Physikalisch-Chemisches Institut der Universitaet Zuerich
 Tel: +41 44 63 54 497  /  Mobile: +41 79 71 90 935


On Fri, 15 Nov 2013, Jack Davis wrote:

Dear Forum,

I’m trying to calculate surface energies using PWscf, however, I am unsure of the methodology. To begin with we calculate the bulk energy of the FCC unit cell, using the attached input. We then calculate the energy of a 111 slab, 10 layers thick with a 6 atom vacuum gap. The surface energy is then calculated as,

Surface energy = Energy of slab - (bulk energy * 10) / 2.

I think I am probably misunderstanding the energies PWscf is giving me. We’re getting some strange answers!

Thank you,
Jack Davis

School of Chemistry
University of Birmingham
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