[gpaw-users] Fwd: slab-calculations

[Nichols A. Romero]

Looks like you need a wavelet code that supports exact exchange with periodic
boundary conditions. I know of one that will support that in about a year
from now.

Nichols A. Romero, Ph.D.
Argonne Leadership Computing Facility
Argonne National Laboratory
Building 240 Room 2-127
9700 South Cass Avenue
Argonne, IL 60490
(630) 252-3441


----- Original Message -----
From: "Peter Deák" <peter.deak at bccms.uni-bremen.de>
To: gpaw-users at listserv.fysik.dtu.dk
Sent: Friday, October 28, 2011 7:08:22 AM
Subject: Re: [gpaw-users] Fwd:  slab-calculations

> One should also note that muffin-tin like approach does not solve the problem of 
> wasting grid-points/planewaves in the vacuum region, the required resolution is 
> still determined mostly by the regions between atoms.
> 
> As Jens pointed out, also LCAO provides variable resolution, the accuracy of 
> calculation can be just more difficult to control.
> 
> Best regards,
> Jussi

Well, you are absolutely right, and that's why LCAO is not a really good solution for me, being interested in defects: it does not work well in the interstitial region or for vacancies. If one had different grid spacings around atoms and in the "interstitial" parts, it would help also in the vacuum.  The resolution needed in the interstital region is not so high as in the "atomic spheres" so one would still economize. But I guess, if having different grids in the slab and in the vacuum layer is difficult, the muffin-tin idea would be a lot harder.

I am really hard pressed for I have to consider 100-300 atoms at PBE0 level. In bulk no problem with VASP but for clusters or slabs just no way. 

Regards

Peter

_________________________________________________
Peter Deak
Bremen Center for Computational Materials Science
Universität Bremen
P.O.Box 330 440
28334   Bremen
Germany
Tel: 0421/218-62353
Fax: 0421/218-62770
e-mail: deak at bccms.uni-bremen.de
http://www.bccms.uni-bremen.de/cms/people/p_deak/


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