Polarization corrections to core levels
(1969) In Journal of Physics B: Atomic and Molecular Physics 2(12). Abstract
 Theoretical predictions for ionization energies of inner core electrons generally come out much more accurately by taking the difference between the total energies of two selfconsistent HartreeFock calculations than by using Koopmans' theorem. For the outer core electrons, on the other hand, little or no improvement over Koopmans' theorem is obtained from a `ΔSCF method'.
We show here that the difference between the results from the ΔSCF method and from Koopmans' theorem can be expressed in terms of a polarization potential. A simple physical argument can then be made as well as a comparison with secondorder perturbation theory, which both show why the ΔSCF method should give good results for inner core levels but not... (More)  Theoretical predictions for ionization energies of inner core electrons generally come out much more accurately by taking the difference between the total energies of two selfconsistent HartreeFock calculations than by using Koopmans' theorem. For the outer core electrons, on the other hand, little or no improvement over Koopmans' theorem is obtained from a `ΔSCF method'.
We show here that the difference between the results from the ΔSCF method and from Koopmans' theorem can be expressed in terms of a polarization potential. A simple physical argument can then be made as well as a comparison with secondorder perturbation theory, which both show why the ΔSCF method should give good results for inner core levels but not necessarily for outer core levels.
The formulation in terms of a polarization potential allows a systematic discussion and an easy calculation of chemical shifts in core levels. We find that the core electrons serve as probes on the charge density and the polarizability of the valence electron system. As numerical examples, results are given for ions, atoms and metals of sodium and potassium. The limitations and possible extensions of the theory are discussed. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/record/8778129
 author
 Hedin, Lars ^{LU} and Johansson, Arne
 organization
 publishing date
 1969
 type
 Contribution to journal
 publication status
 published
 subject
 in
 Journal of Physics B: Atomic and Molecular Physics
 volume
 2
 issue
 12
 external identifiers

 scopus:0014625919
 DOI
 10.1088/00223700/2/12/313
 language
 English
 LU publication?
 yes
 id
 1124cf0ea34e4ef5ab515d98044f2f2d (old id 8778129)
 date added to LUP
 20160304 09:28:22
 date last changed
 20180107 11:04:55
@article{1124cf0ea34e4ef5ab515d98044f2f2d, abstract = {Theoretical predictions for ionization energies of inner core electrons generally come out much more accurately by taking the difference between the total energies of two selfconsistent HartreeFock calculations than by using Koopmans' theorem. For the outer core electrons, on the other hand, little or no improvement over Koopmans' theorem is obtained from a `ΔSCF method'.<br/><br> <br/><br> We show here that the difference between the results from the ΔSCF method and from Koopmans' theorem can be expressed in terms of a polarization potential. A simple physical argument can then be made as well as a comparison with secondorder perturbation theory, which both show why the ΔSCF method should give good results for inner core levels but not necessarily for outer core levels.<br/><br> <br/><br> The formulation in terms of a polarization potential allows a systematic discussion and an easy calculation of chemical shifts in core levels. We find that the core electrons serve as probes on the charge density and the polarizability of the valence electron system. As numerical examples, results are given for ions, atoms and metals of sodium and potassium. The limitations and possible extensions of the theory are discussed.}, author = {Hedin, Lars and Johansson, Arne}, language = {eng}, number = {12}, series = {Journal of Physics B: Atomic and Molecular Physics}, title = {Polarization corrections to core levels}, url = {http://dx.doi.org/10.1088/00223700/2/12/313}, volume = {2}, year = {1969}, }