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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>Dear QE developers and users:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>This is kind of follow-up question of my previous post: <a href="http://www.democritos.it/pipermail/pw_forum/2011-December/022823.html">http://www.democritos.it/pipermail/pw_forum/2011-December/022823.html</a><o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>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 ( <a href="http://www.democritos.it/~fabris/Ce4_ps_f1d1-pbe-rc1.0.uspp.UPF">http://www.democritos.it/~fabris/Ce4_ps_f1d1-pbe-rc1.0.uspp.UPF</a> ) and tried it with current O psp. The Ce psp is ultrasoft and the O psp is RRKJ. Both use PBE functionals. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>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 <a href="http://prb.aps.org/abstract/PRB/v75/i4/e045121">http://prb.aps.org/abstract/PRB/v75/i4/e045121</a> . As relax from case 2) doesn’t do much, final structures from two cases are identical. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>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…<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>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. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Any comments or suggestions…???<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><i><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>-------<br>Chan-Woo Lee, Ph.D.<o:p></o:p></span></i></p><p class=MsoNormal><i><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Postdoctoral Research Associate<o:p></o:p></span></i></p><p class=MsoNormal><i><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'><o:p> </o:p></span></i></p><p class=MsoNormal><i><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Department of Chemistry<br>University of Pennsylvania<br>231 South 34th Street<br>Philadelphia, PA 19104-6323 <br><br><br></span></i><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'><o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>