No, I don't think so. Every calculation uses its own Energy-zero (the average of the Coulomb-potential in the interstitial region is set to zero), so clearly one must use EF and E-2p from the same (half-core hole) calculation.
Eventually, you can check the k-mesh, as with a small k-mesh, EF could vary a bit. (I hope you have used "comparable k-meshes". This means the mesh for the 2x2x1 supercell should be by by a factor of two smaller in x,y than for the primitive cell (eg. 2x2x2 vs 4x4x2) Am 10.04.2015 um 19:33 schrieb David Olmsted:
I am modeling XPS binding energy using a half core-hole, offset by background charge. As I understand the method that has been explained here recently, one computes the binding energy as the energy of the state from case.scfc minus the Fermi energy from ':FER' in case.scf. Should the Fermi energy be for the configuration with the half core-hole, or a configuration without the core-hole? As explained below, from my results it looks as if it should be the same configuration, but without the core hole. Some details: Version 14.2 I am computing the differences in the XPS binding energy for Al-2p for cyrstals in the Al-P-O-H system to see how the binding energy changes between hydrated and non-hydrated configurations. This is for comparison with experimental results. (The actual material is amorphous, but I am hoping the effects of on the spectra will be at least qualitatively similar.) The simplest structure is AlPO4, berlinite. I have run two configurations, the primitive cell with 18 atoms, including 3 Al atoms, and a 2x2x1 supercell. In each case I have made one Al unique, then added one-half core-hole in case.inc and offset it with -0.5 background charge in case.inm. For simplicity I will show the results just for the triplet state. Lines are from case.scf and case.scfc. -------- 2x2x1 supercell, no core-hole :LABEL4: using the command: run_lapw -ec 0.00001 -p <skip> :FER : F E R M I - ENERGY(TETRAH.M.)= 0.0547409802 :NEC01: NUCLEAR AND ELECTRONIC CHARGE 720.00000 720.00112 :NEC02: NUCLEAR AND ELECTRONIC CHARGE 720.00000 720.00000 :NEC03: NUCLEAR AND ELECTRONIC CHARGE 720.00000 720.00000 -------- primitive cell, no core-hole :LABEL4: using the command: run_lapw -ec 0.00001 -p -NI <skip> :FER : F E R M I - ENERGY(TETRAH.M.)= 0.0564539224 :NEC01: NUCLEAR AND ELECTRONIC CHARGE 180.00000 180.00073 :NEC02: NUCLEAR AND ELECTRONIC CHARGE 180.00000 180.00000 :NEC03: NUCLEAR AND ELECTRONIC CHARGE 180.00000 180.00000 -------- 2x2x1 supercell, half core-hole :LABEL4: using the command: run_lapw -ec 0.00001 -p <skip> :WARN : CHARGED CELL with -0.500 :FER : F E R M I - ENERGY(TETRAH.M.)= 0.0609755546 :NEC01: NUCLEAR AND ELECTRONIC CHARGE 719.50000 719.50115 :NEC02: NUCLEAR AND ELECTRONIC CHARGE 719.50000 719.50000 :NEC03: NUCLEAR AND ELECTRONIC CHARGE 719.50000 719.50000 <case.scfc> :2P 001: 2P -5.274530454 Ry ------- primitive cell, half core-hole :LABEL4: using the command: run_lapw -ec 0.00001 -p -NI :WARN : CHARGED CELL with -0.500 :FER : F E R M I - ENERGY(TETRAH.M.)= 0.0944258517 :NEC01: NUCLEAR AND ELECTRONIC CHARGE 179.50000 179.50067 :NEC02: NUCLEAR AND ELECTRONIC CHARGE 179.50000 179.50000 :NEC03: NUCLEAR AND ELECTRONIC CHARGE 179.50000 179.50000 <case.scfc> :2P 001: 2P -5.268297265 Ry -------------- The energy of the state differs by 6 mRy (85 meV) between the supercell and the primitive cell, making me hopeful that the supercell is reasonably converged as to size. The Fermi energy, though differs by 40 mRy (540 meV), so probably the supercell is not converged with respect to size for the Fermi energy. In the limit of a large supercell, it would seem that the Fermi energy should converge to the Fermi energy for the configuration without the core hole. So it seems to me that I should use the Fermi energy from the configuration without the core-hole and compute the binding energy as -5.2745 - 0.0547 = -5.329 Ry. Is this correct? Thanks, David David Olmsted Assistant Research Engineer Materials Science and Engineering 210 Hearst Memorial Mining Building University of California Berkeley, CA 94720-1760 _______________________________________________ Wien mailing list [email protected] http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/[email protected]/index.html
-- ----------------------------------------- Peter Blaha Inst. Materials Chemistry, TU Vienna Getreidemarkt 9, A-1060 Vienna, Austria Tel: +43-1-5880115671 Fax: +43-1-5880115698 email: [email protected] ----------------------------------------- _______________________________________________ Wien mailing list [email protected] http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/[email protected]/index.html
