Dear Dr. Toffoli thanks for putting your comments and interest in this matter.
The pbe pseudopotential that I took from pwscf already has 5S, 5P, 5D, 6S and 6P orbitals included. I am not sure whether inclusion of more orbitals (4P at least) would make any difference. We can give it a try. yesterday I tried with Ba and O GGA pseudopotentials taken from ABINIT. they are norm conserving ones. I found the lattice constant for BaO too much overestimated. I will let you know if I find some more information. regards munima > Dear Munima, > > I also ran into the exact same problem just yesterday using the PBE > pseudopotential from the web site. The lattice constant that you quote is > almost identical to the one I obtained. Inspired by your post, I > calculated > the lattice constant for BaS to compare to the result in the paper you > quote and it matches better (almost the same as the experimental value). I > don't know if this is supposed to make us feel better. > > I also thought of generating a new pseudopotential but as far as I know, > the generator cannot include two orbitals of the same l even though they > might be from different shells. Thus we couldn't include 5s and 6s > orbitals > simultaneously. Am I right? >I would also appreciate thoughts on what we > could do or pseudopotentials that have been converted from other codes if > there are any lying around. > > Thank you very much. > > Best, > Hande > > On Fri, 1 Aug 2008, Paolo Giannozzi wrote: > >> >> On Jul 23, 2008, at 7:58 , Munima Bora Sahariah wrote: >> >> > For last couple of days I have been trying to find the equilibrium >> > lattice >> > constant of BaO with GGA (pw91) and has found that my calculated >> > value >> > underestimates the experimental one by 1.3% (GGA = 10.301 a.u., EXP = >> > 10.431 a.u.). Surprizingly, while trying with LDA, I obtained a value >> > which is closer to the experimental one as compared to GGA (LDA = >> > 10.324 >> > a.u.) [...] >> > While doing a search on the web, I found one paper (Phys. Rev. B 71, >> > 085203) where GGA and LDA results for lattice constant of BaO have >> > been >> > listed. In this paper calculations were done in CASTEP. Here the >> > LDA value >> > underestimates the experimental lattice constant while the GGA >> > (pw91) value >> > improves the situation and is closer to the experimental one. >> >> try different pseudopotentials if you can: this might be one of those >> cases >> in which the results are more sensitive than desired to the quality of >> pseudopotentials (in particular of Ba). >> >> Paolo >> --- >> Paolo Giannozzi, Dept of Physics, University of Udine >> via delle Scienze 208, 33100 Udine, Italy >> Phone +39-0432-558216, fax +39-0432-558222 >> >> >> >> _______________________________________________ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/mailman/listinfo/pw_forum >> > > -- > Hande Toffoli > Department of Physics > Office 439 > Middle East Technical University > Ankara 06531, Turkey > Tel : +90 312 210 3264 > http://www.physics.metu.edu.tr/~hande > > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > ----------------------------------------------------------------------------------- This email was sent from IIT Guwahati Webmail. If you are not the intended recipient, please contact the sender by email and delete all copies; your cooperation in this regard is appreciated. http://www.iitg.ac.in
