Looking at the output, I would initially increase the mesh cutoff to at least 250 Ry (N has a rather hard pseudo) and see if anything improves.
Marcos > Hi Marcos, > Attached please find the input file for generation Ga and N PP, the PP > files for Ga and N, the input file for seista and the outfile file(out). > For wurtize GaN, three parameters should be optimized(a,c,u),so the > fractional coordinate can't be fixed. > Really thank you very much. > Mu > > Quoting Marcos Verissimo Alves <[EMAIL PROTECTED]>: > >> Hi Mu, >> >> I don't really get what you mean by single-point calculation - I'll >> assume >> it is just geometry relaxation. You should do both, one as a check of the >> other, in my opinion. In principle, if your pseudos are ok and your >> parameters (namely k-point sampling, mesh cutoff, basis set size and >> electronic temperature) are ok, then I guess there should not be too much >> difference between the results of an E vs a curve and a variable cell >> calculation. Would you mind posting the pseudopotentials and input so we >> can look at it? >> >> Siesta has no way of maintaining symmetry. I have seen a few suggestions >> on how to do this on the list, like entering fractional coordinates and >> fixing them, but I don't know if this would work or give sensible results >> at all - mainly because I haven't tried. >> >> Cheers, >> >> Marcos >> >>> Hi Marcos, >>> Thank you very much. >>> I have generated a N pseudo using LDA since I want to use this method >>> in the following calculations. I checked it for NO molecule.The >>> optimized bond length is in excellent agreement with experiments. >>> I want to optimize the lattice parameter for wurtzite GaN. Should I do >>> single point calculation or define MD.TypeOfRun cg and MD.Variable-Cell >>> T?If I choose the latter, the shape of the cell is changed after >>> optimization and the symmetry is completely broken.Is there any way to >>> keep symmetry during calculation?The difference between calculations >>> and experiments is large, about 10% error for a and c. >>> It seems that the compiler is ok.I will try to include the 3d states of >>> Ga. >>> Once again, thank you very much. >>> Mu >>> >>> >>> Quoting Marcos Verissimo Alves <[EMAIL PROTECTED]>: >>> >>>> Hi Mu, >>>> >>>> There is a good N pseudo on the siesta website, but it's gga - however >>>> uses partial core, so it might be a good idea to include partial core >>>> also >>>> for N. There is one thing that is always worth reminding - check what >>>> compiler you are using for compiling atom. I remember last year (maybe) >>>> someone wrote to the list complaining that her pseudo did not work, >>>> giving >>>> ghost states which did not exist, since the pseudo had already been >>>> used >>>> in previsous work, and it was the compiler's fault. When she changed >>>> the >>>> compiler (or compiling options, I don't remember exactly now) her >>>> pseudo >>>> worked fine. Search the list archives for that issue. >>>> >>>> If the compilation is not really a problem, then it might be good to >>>> include the 4d states for Ga. I agree with Alexander that you might >>>> see a >>>> big difference when you include 4d states as semicore - this is my >>>> experience with Pb in PbO, it only really gave sensible results when I >>>> included the semicore states of Pb. However, I'm not sure I agree >>>> completely that DZ would definitely not be enough. DZ might not give >>>> you >>>> the best results ever, but would not be the worse ever, either. How >>>> much >>>> is the difference of lattice parameter from experimental value you >>>> obtain? >>>> Remember that ~2% would be ok for LDA. >>>> >>>> Hope this helps, >>>> >>>> Marcos >>>> >>>>> hello, >>>>> I want to generate the pseudopotential of Ga and N for GaN bulk. >>>>> For Ga the input file is as follows: >>>>> pe Ga, LDA, rcore=0.80 >>>>> tm2 0.0 >>>>> n=Ga c=car >>>>> 0.0 0.0 0.0 0.0 0.0 0.0 >>>>> 6 2 >>>>> 4 0 2.00 0.00 # 4s2 >>>>> 4 1 1.00 0.00 # 4p1 >>>>> 2.10 2.50 3.00 0.00 0.00 0.80 >>>>> For N the input file is as follows: >>>>> pg Nitrogen >>>>> tm2 0.0 >>>>> N car >>>>> 0.0 0.0 0.0 0.0 0.0 0.0 >>>>> 1 2 2 0 2.00 0.00 2 >>>>> 1 3.00 0.00 1.14 1.14 1.14 0.00 >>>>> 0.00 0.00 >>>>> The reference electronic configuration and s/p/d cutoff radius (except >>>>> the parameter for core correction)are cited from PRB,70,235209, where >>>>> the lattice constant of GaN agrees well with experiments.In their work >>>>> it has been tested that the 3d of Ga can be left in the core. >>>>> But however I adjust the r(pc)for core correction, the optimized >>>>> lattice constant differs greatly from experiment.(DZ basis set is >>>>> employed) >>>>> Is anyone who have good idea on how to generate good pseudopotential >>>>> for GaN bulk?Thank you very much. >>>>> Mu >>>>> >>>> >>>> >>>> -- >>>> Dr. Marcos Verissimo Alves >>>> Post-Doctoral Fellow >>>> Condensed Matter and Statistical Physics Sector >>>> International Centre for Theoretical Physics >>>> Trieste, Italy >>>> >>>> -------- >>>> >>>> I have become so addicted to vi that I try to exit OpenOffice by typing >>>> :wq! >>>> >>>> >>>> >>> >> >> >> -- >> Dr. Marcos Verissimo Alves >> Post-Doctoral Fellow >> Condensed Matter and Statistical Physics Sector >> International Centre for Theoretical Physics >> Trieste, Italy >> >> -------- >> >> I have become so addicted to vi that I try to exit OpenOffice by typing >> :wq! >> >> >> > > > -- Dr. Marcos Verissimo Alves Post-Doctoral Fellow Condensed Matter and Statistical Physics Sector International Centre for Theoretical Physics Trieste, Italy -------- I have become so addicted to vi that I try to exit OpenOffice by typing :wq!
