N.B., there can also be a discontinuity in the charge (small) due to the tails of the core states which can be eliminated by doing "touch .lcore".
On Mon, Nov 21, 2016 at 8:36 AM, Laurence Marks <[email protected]> wrote: > APW+lo methods have a step in the gradient of the density at the RMT. To > avoid this use a lapw basis set: to reduce it increase RKMAX. > > --- > Professor Laurence Marks > "Research is to see what everybody else has seen, and to think what nobody > else has thought", Albert Szent-Gyorgi > http://www.numis.northwestern.edu > Corrosion in 4D http://MURI4D.numis.northwestern.edu > Partner of the CFW 100% gender equity project, www.cfw.org/100-percent > Co-Editor, Acta Cryst A > > > On Nov 21, 2016 07:39, "John Rundgren" <[email protected]> wrote: > >> Dear Peter Blaha and Gavin Abo, >> >> Non-overlapping muffin-tin spheres are used by WIEN2k and my LEED program >> eeasisss (Elastic Electron-Atom Scattering in Solids and Surface Slabs). >> But RMT(setrmt_lapw) is not automatically the best choice for >> RMT(eeasisss). LEED touching radii of atoms depend on exchange-correlation >> interaction between crystal electron gas (the WIEN2k electrons) and an >> incident LEED electron (energy 20-500 eV). >> >> This is a N+1 electron scattering situation, where "N" signifies the >> WIEN2k electrons and "1" an alien LEED electron. >> >> W2k can be reconciled with LEED using an atomic sphere approximation >> (ASA) extending into the Fourier expansion realm of W2k. A while ago you >> (P.B. and G.A.) suggested an ASA routine, in which I now use Poisson >> differentiation of vcoul_ASA in order to obtain clmsum_ASA. I consider the >> case LM=(0,0), sufficient for current LEED. >> >> The considered structure is a supercell = a surface slab 15 layers thick, >> where layers 1-2 and 14-15 are C-O and O-C, respectively. Mirror symmetry >> about layer 8. At the C-O layers vcoul_ASA(0,0) is continuous across the >> RMT radius, but clmsum_ASA(0,0) versus radius shows a step of the order of >> 10%. >> >> Is the step k-point dependent? It does not seem so. With 16 and 48 >> k-points the clmsum_ASA(0,0) steps are preserved within 6 digits. >> >> I shall be glad to supply the code. When the described numerical error is >> fixed, WIEN2k and eeasisss can be re-run self-consistently within the model >> of non-overlapping muffin-tin atoms. >> >> Regards, >> John Rundgren >> >> KTH >> >> >> >> -- Professor Laurence Marks "Research is to see what everybody else has seen, and to think what nobody else has thought", Albert Szent-Gyorgi www.numis.northwestern.edu ; Corrosion in 4D: MURI4D.numis.northwestern.edu Partner of the CFW 100% program for gender equity, www.cfw.org/100-percent Co-Editor, Acta Cryst A
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