I strongly suggest that you research the basis for the Slater 1/2 method as well as extensions. What Slater suggested is that an integral from the initial state (no core hole) and the final state (complete core hole) could be approximated by the midpoint (1/2 core hole). One can do better, albeit it will take more calculations, for instance consider more fractional holes (e.g. 1/4, 3/4) then integrate better.
No core hole assumes that your switch electron has passed before the system can respond -- which is dubious because the temporal coherence (width along the beam direction) is large, typically 100nm or so. A full core hole assumes that the swift electron hangs around for a long time so sees more of the final state, also not a very convincing argument for current microscopes. (Let's ignore femtosecond EM.) N.B., describing the swift electron correctly via mutual coherence (effectively a density matrix) is not common. We had a go in Ultramicroscopy 55 (1994) 165 at the spatial description, if you dig you may find papers where the temporal part has been included. I have not fully tracked the literature on this. At least in standard models, the initial and final spin states should be the same -- exchange coupling of a TEM electron and the solid is essentially zero. (With SOC I am not sure exactly what should be done.) I am not aware of calculations where this constraint has been enforced, although there may be some. (I have checked this myself for some transition metal oxides and it matters.) I very strongly suspect that in some of the literature calculations the final spin-state differs from the original, so the results have a buried incorrect approximation. Thus, if you take 1/2 (or other) electrons out of the core then in my opinion you need to ensure that the initial and final spin states (all electrons) are the same, e.g. use runfsm. Unfortunately you might still have a different local spin state which at least at present Wien2k cannot handle. On Sun, Nov 17, 2019 at 9:41 AM 丁一凡 <yfding0...@foxmail.com> wrote: > Respected Prof. Marks, > > I remember 1/2 core hole calculations in this article "Partial core hole > screening in the Cu L-3 edge" (DOI:10.1007/s100510170179). When calculating > my systems, I only used a full core hole and supercell. I will follow your > suggestion and try it. In the previous calculation, I didn't notice the > relation between spin and core hole. Please allow me to ask a question > here, why is runfsm the best method ? > _______________________________________________ > Wien mailing list > Wien@zeus.theochem.tuwien.ac.at > > https://urldefense.proofpoint.com/v2/url?u=http-3A__zeus.theochem.tuwien.ac.at_mailman_listinfo_wien&d=DwICAg&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=IaYA9EMobH_kt7vz-PIZQe9kfpg3FT2--xUJQ2Ab52I&s=VAJEsdWNwMXjnX7a6vqaWdmGZZ0LxAyqLZiCi-twZKM&e= > SEARCH the MAILING-LIST at: > https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mail-2Darchive.com_wien-40zeus.theochem.tuwien.ac.at_index.html&d=DwICAg&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=IaYA9EMobH_kt7vz-PIZQe9kfpg3FT2--xUJQ2Ab52I&s=bIndfEmmbUY8Vn29vIBEfrrBcS1ufsDySR2edvgq9uc&e= > -- Professor Laurence Marks Department of Materials Science and Engineering Northwestern University www.numis.northwestern.edu Corrosion in 4D: www.numis.northwestern.edu/MURI Co-Editor, Acta Cryst A "Research is to see what everybody else has seen, and to think what nobody else has thought" Albert Szent-Gyorgi
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