Dear QE developers and users:
This is kind of follow-up question of my previous post: http://www.democritos.it/pipermail/pw_forum/2011-December/022823.html I found that current Ce psp has some critical problems (for both CeO2 and Ce2O3) and tried to modify the psp. In doing so, I found Ce psp from Prof. Fabris ( http://www.democritos.it/~fabris/Ce4_ps_f1d1-pbe-rc1.0.uspp.UPF ) and tried it with current O psp. The Ce psp is ultrasoft and the O psp is RRKJ. Both use PBE functionals. In working with the psp, I found interesting results. I tried two cases: 1) SCF without any atomic relaxation 2) RELAX. I use QE 4.3.2 and Effective U is chosen as 5.0. Initial structures are adopted from http://prb.aps.org/abstract/PRB/v75/i4/e045121 . As relax from case 2) doesn't do much, final structures from two cases are identical. While the structures are identical, occupation of f orbitals are different and DOS are also not the same. For 1) case, occupation is almost 1.0 (~0.9) at single orbital state which is desirable, I think. Also, DOS shows that there is no partially filled f states near Fermi level which is the case for conventional DFT. So, Ce2O3 is predicted to be insulating. For 2) case, occupations are somewhat even: 0.23, 0.26, 0.29, and 0.12.. Also, electronic structure doesn't change that much and there is still partially filled f states. Same atomic structures but totally difference electronic structures. While I tried to understand and explain this to myself, I can't find any good answers for this. I am currently testing "starting_ns_eigenvalue" and "mixing_fixed_ns" to see forcing certain occupations will be helpful or not.. but I am not sure. Any comments or suggestions.??? ------- Chan-Woo Lee, Ph.D. Postdoctoral Research Associate Department of Chemistry University of Pennsylvania 231 South 34th Street Philadelphia, PA 19104-6323 -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20120202/e36bb9b4/attachment-0001.htm
