I don't know the details of the generation of this particular PP but in the old good times there has been a very detailed comparison of LDA band structure calculation of Ge and GaAs between the PP method and LMTO [GB Bachelet and NE Christensen, Phys.Rev.B 31, 879 (1985) ]. The main result is that in order to get the correct (bad) gap in Ge and GaAs 1) scalar relativistic, 2) spin-orbit coupling, 3) 3d-state relaxation are important... not to mention convergence w.r.t. to cutoff ...
Hope this helps, Stefano de Gironcoli - SISSA and DEMOCRITOS willy kohn wrote: > Hi, Axel: > > Well, I didn't blame the PP, and I didn't mean to. My question is > quite simple. I was told that with a LDA PP, Ge has a vanishing or > negative band gap at Gamma point. But with this PP, it has a gap of > 0.50 eV (using experimental lattice) or 0.80 eV (after relaxation). > I'm not sure what I knew is correct, and that is the reason I wanted > another PP to verify. > > Best, > > Wei > > On Thu, Oct 2, 2008 at 2:12 PM, Axel Kohlmeyer > <akohlmey at cmm.chem.upenn.edu <mailto:akohlmey at cmm.chem.upenn.edu>> > wrote: > > On Thu, 2 Oct 2008, willy kohn wrote: > > WK> Hi, Axel: > WK> > WK> Thanks a lot for your quick answer. I need to do some > calculations on some > WK> compound semiconductors of Ge. But the PP (Ge.pz-bhs.UPF) > provided in the > WK> PWSCF website yeided some results that I don't understand. So > I would like > > perhaps it would be useful to explain in more detail what > is confusing you and what calculation you did with what input. > perhaps some people here can comment on it. it is always easy > to blame the pseudopotential (sometimes rightfully so), but > more often than not, the real cause is in not doing a calculation > correctly, or not using a pseudopotential correct. > > WK> to use some other PP's to check if I did the calculation > correctly. Any > WK> suggestions? > > i have a set of Ge pseudopotentials generated from parameters > for a norm-conserving troullier-martins potential that is in > the extended CPMD psp library. they have seen only very minimal > transferability testing (using an atomic code in bessel basis), > but so far seem to be ok, except for the OLYP one which has a > ghost in the s-channel. > > i can send them to you in a private mail, if you are interested. > no guarantees etc... > > cheers, > axel. > > WK> > WK> Best, > WK> > WK> Wei > WK> > WK> On Thu, Oct 2, 2008 at 11:54 AM, Axel Kohlmeyer > <akohlmey at cmm.chem.upenn.edu <mailto:akohlmey at cmm.chem.upenn.edu> > WK> > wrote: > WK> > WK> > On Thu, 2 Oct 2008, willy kohn wrote: > WK> > > WK> > WK> Dear PWSCF users: > WK> > WK> > WK> > WK> I have a quick question about using > WK> > WK> Hartwigsen-Goedeker-Hutter< > WK> > > > http://cvs.berlios.de/cgi-bin/viewcvs.cgi/cp2k/potentials/Goedecker/abinit/pade > WK> > >pseudopotential > WK> > WK> with PWSCF. Is there any converter to transfer the HGH pp > WK> > WK> format to UPF used in PWSCF? > WK> > > WK> > none that i am aware of. > WK> > > WK> > the GTH pseudopotentials are analytical in real and reciprocal > WK> > space and to incorporate them properly, one would have to do a > WK> > lot of programming. in the CPMD code (from http://www.cpmd.org) > WK> > they are treated as a special case, similar to ultra-soft psps. > WK> > > WK> > is there any particularly reason you'd need any of those? > WK> > > WK> > cheers, > WK> > axel. > WK> > > WK> > > WK> > WK> > WK> > WK> Best, > WK> > WK> > WK> > WK> Wei > WK> > WK> > WK> > WK> Georgia Tech > WK> > WK> > WK> > > WK> > -- > WK> > > ======================================================================= > WK> > Axel Kohlmeyer akohlmey at cmm.chem.upenn.edu > <mailto:akohlmey at cmm.chem.upenn.edu> http://www.cmm.upenn.edu > WK> > Center for Molecular Modeling -- University of > Pennsylvania > WK> > Department of Chemistry, 231 S.34th Street, Philadelphia, PA > 19104-6323 > WK> > tel: 1-215-898-1582, fax: 1-215-573-6233, office-tel: > 1-215-898-5425 > WK> > > ======================================================================= > WK> > If you make something idiot-proof, the universe creates a > better idiot. > WK> > > WK> > > -- > ======================================================================= > Axel Kohlmeyer akohlmey at cmm.chem.upenn.edu > <mailto:akohlmey at cmm.chem.upenn.edu> http://www.cmm.upenn.edu > Center for Molecular Modeling -- University of Pennsylvania > Department of Chemistry, 231 S.34th Street, Philadelphia, PA > 19104-6323 > tel: 1-215-898-1582, fax: 1-215-573-6233, office-tel: 1-215-898-5425 > ======================================================================= > If you make something idiot-proof, the universe creates a better > idiot. > > > ------------------------------------------------------------------------ > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum >
