[Pw_forum] vc-relax, GGA
> > Dear Santos Using vc-relax variable, all cell parameters ( distances and angles) are optimized so one may obtain some parameters lower than expected. Did you consider symmetry in your job or not? this would affect the resuls. I think that your obtained value is plausible. vc-relaxed calculation in quantum espresso works very well and effective. Best Wishes Masoud Nahali SUT > Hello PWscf users. I optimize a triclinic cell using the vc-relax, GGA > functional. My expectation was that all values of the calculated parameters > were > slightly higher than the respective experimental values. But, the angle > alpha > showed a value slightly lower. The experimental value is in degree, 103.32, > the > calculated value is 102.6. There is some inconsistency in this result? > > Sincerely, > A. S. Santos > > Univesidade Federal Fluminense > Niter?i-Rio de Janeiro-Brasil > > > > -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20100824/19c8ccef/attachment.htm
[Pw_forum] vc-relax, GGA
GGA results tend to overestimate the lattice parameters where as LDA results tend to underestimate the lattice parameters. Check how much is the error% in your DFT calculations. regards, On Tue, Aug 24, 2010 at 12:35 PM, ?lvaro Alves wrote: > Hello PWscf users. I optimize a triclinic cell using the vc-relax, GGA > functional. My expectation was that all values of the calculated > parameters were slightly higher than the respective experimental values. But, > the angle alpha showed a value slightly lower. The experimental value is > in degree, 103.32, the calculated value is 102.6. There is some > inconsistency in this result? > > Sincerely, > A. S. Santos > Univesidade Federal Fluminense > Niter?i-Rio de Janeiro-Brasil > > > > > > > > > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > > -- Karthik Guda Graduate Student Materials Engineering Purdue University -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20100824/c2e706b0/attachment.htm
[Pw_forum] vc-relax, GGA
Hello PWscf users. I optimize a triclinic cell using the vc-relax, GGA functional. My expectation was that all values of the calculated parameters were slightly higher than the respective experimental values. But, the angle alpha showed a value slightly lower. The experimental value is in degree, 103.32, the calculated value is 102.6. There is some inconsistency in this result? Sincerely, A. S. Santos Univesidade Federal Fluminense Niter?i-Rio de Janeiro-Brasil -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20100824/f0ae27b1/attachment-0001.htm
