Hi Riccardo We have same kind of problem/observation. We are using Siesta with LDA (DZP basis) and it produces an indirect band gap of 0.70 eV. We have also tested with plane waves basis using Abinit (cutoff = 95 Ry) and found 0.58 eV. Chelikowsky et el. (PRB, 40, 1989) using plane waves report an indirect band gap of 0.81 eV. Wang et el. (PRB, 24, 1981) using LCGO have reported a band gap of 0.52 eV.
Regards, Rafi Ullah On Thu, Feb 6, 2014 at 3:43 PM, Riccardo Rurali <[email protected]> wrote: > Dear Siesters, > > I am having trouble with Ge in LDA with Siesta. > > As is well-known, Ge is a pathological case within DFT-LDA: the gap > shrinks so much that is becomes negative, i.e. Ge is metallic in LDA. > > However, I'm having problems in recovering this behavior with Siesta and I > get gaps of 0.4-0.5eV, depending on fine details of the basis set. > > I have tried both optimized and automatic DZP basis sets. Short and long. > "Vanilla" pseudos or pseudos with extra tuning (e.g. core-corrections). > Nothing. The gap's still there. > > Has any of you experience with treating Ge with Siesta ans trying to > recover to "right" (which is wrong in reality...) LDA behavior? > > Any help would be greatly appreciated. > > Riccardo > > -- > > Riccardo Rurali > Institut de Ciència de Materials de Barcelona (ICMAB) > Consejo Superior de Investigaciones CientÃficas (CSIC) > Campus de Bellaterra > 08193 Bellaterra (Barcelona) > Spain > > tel.: +34 93 5801853 ext. 347 > e-mail: [email protected] > http://www.icmab.es/dmmis/leem/ > > Man, the dope's that there's still hope > > -- ------------------------------------------------------ Ph.D. Student Theory Group CIC nanoGUNE, Tolosa Hiribidea, 76 E-20018 Donostia-San Sebastian Spain +34 943 574 063 [email protected] www.nanogune.eu ------------------------------------------------------
