Hola Ricardo, Normally I'd go search for the reference but right now I'm busy as hell... So, two questions:
1) "x-potential" would refer to the exchange part of the exchange and correlation potential? 2) Is it a hybrid functional? Cheers, Marcos On Tue, Jun 15, 2010 at 6:38 PM, Ricardo Faccio <[email protected]> wrote: > A short comment GAPS > Recently Trand & Blaha PRL 102, 226401 (2009) presented a modified > version of the x-potential proposed by Becke & Johnson [J. Chem. Phys. > (2006)] calculating band gaps for solids with an accuracy similar to GW and > Experiments. This new flavor have been recently added to the new version > WIEN2k. > I fastly tested rutile and antase, finding Egap= 2.73 eV and 3.04 eV > respectively > It is efficient and parameter free (in difference to DFT+U). > Best regards > Ricardo > ------------------------------------------------------------------------- > Dr. Ricardo Faccio > Prof. Adjunto de Física > Mail: Cryssmat-Lab., Cátedra de Física, DETEMA > Facultad de Química, Universidad de la República > Av. Gral. Flores 2124, C.C. 1157 > C.P. 11800, Montevideo, Uruguay. > E-mail: [email protected] > Phone: 598 2 924 98 59 > 598 2 929 06 48 > Fax: 598 2 9241906 > Web: http://cryssmat.fq.edu.uy/ricardo/ricardo.htm > > --------------------------------------------------------------------------------- > ----- Original Message ----- From: Marcos Veríssimo Alves > To: [email protected] > Sent: Tuesday, June 15, 2010 1:25 PM > Subject: Re: [SIESTA-L] Band Gap Help > > > > Robert, > > > Rutile is a widely studied system, so there should be accurate plane-wave > calculation in the literature for you to compare your result. LDA can indeed > seriously underestimate band gaps, and even render insulators metallic > sometimes. I recommend you do a search in the literature and see if other PW > or Siesta/local orbital calculations yield the same result. > > > Marcos > > > On Tue, Jun 15, 2010 at 6:18 PM, Koch, Robert J <[email protected]> wrote: > > Hello All, > > I'd greatly appreciate any advice on the following: > > I'm trying to calculate the band gap of TIO2 (Rutile). I have attached my > fdf file, my pseudo .psf files as well as their input .inp files. > > When I run this and use the eig2dos utility to plot density of states, I > see a band gap of about 1.4 eV which is far too low (should be about 3.3 > eV). I'm aware that typically DFT calculations underestimate the band gap, > but this underestimation seems like a little much. Can anyone make any > recemendations as to how to improve my calculation? I'm quite stuck and not > sure how to proceed. > > Thanks in advance! > Rob Koch >
