[Wien] [SPAM?] Should the valence electrons configuration of charge transfer insulators be changed ?

[Laurence Marks]

To my knowledge, the closest you can come is the LDA 1/2 method, and/or LDA
(or GGA) +U. These are related to what is called the "Slater-Janak
transition state approach", although not many people use it. My group found
it useful for VXPS spectra of some lanthanides, see DOI:
10.1103/PhysRevMaterials.2.025001.

However, I am not sure that this is appropriate for EELS, unless you are
using low energy electrons (e.g. 1-100 eV). For standard core-loss EELS the
changes when using a Slater approach are so large that they will probably
swamp these effects. Also important for conventional EELS are standard
channelling issues -- to my knowledge no code currently can correctly
include both the dynamical diffraction terms and the solid-state transition
terms with full rigor.

On Sun, Nov 17, 2019 at 7:59 AM 丁一凡 <yfding0375 at foxmail.com> wrote:

> As we all know, DFT deals with the system in the ground state. When
> dealing with the charge transfer insulator system, can I modify the valence
> electronic configuration after initialization and before SCF and EELS
> (Electron Energy Loss Spectroscopy) calculations ?
>
> The Cu-based high temperature superconducting (HTSC) oxides are known to
> be insulators of a charge-transfer type, with the charge-transfer (CT) gap
> originating from the energy difference between the O(2p) and the
> Cu(3dx2-y2) orbitals. Before calculating EELS of Cu-based HTSC oxides, will
> it make the result reasonable if their valence electron configuration is
> changed ? For example, we remove one oxygen 2p electron and add one
> electron in Cu 3d orbit. Just like the treatment of core hole effect. For a
> “core-hole” calculation we will edit super.inc and remove one core electron
> from the desired atom and state (1s or 2p, ...). Then we add the missing
> electron either in super.inm (background charge) or super.in2 (add it to
> the valence electrons).
>
> This problem haunts me for several weeks, and my question is still
> unsolved after consulting the previous mailing list. Any comment(s) would
> be highly appreciated. Thanks in advance!
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-- 
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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