Electronic excitations and the Becke-Johnson potential: The need for and the problem of transforming model potentials to functional derivatives
2013 (English)In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 88, no 5, 052519-1-052519-9 p.Article in journal (Refereed) Published
Constructing approximations for the exchange-correlation (xc) potential in density functional theory instead of the energy appears attractive because it may provide for a way of easily incorporating desirable features such as a particle number discontinuity into xc functionals. However, xc potentials that are constructed directly are problematic: An xc potential that is not a priori derived as a functional derivative of some xc energy functional is most likely not a functional derivative of any density functional at all. This severely limits the usefulness of directly constructed xc potentials, e.g., for calculating electronic excitations. For the explicit example of the Becke-Johnson (BJ) potential we discuss defining corresponding energy expressions by density path integrals. We show that taking the functional derivative of these energies does not lead back to potentials that are close to the BJ one, and the new potentials do not share the attractive features of the original BJ expression. With further examples we demonstrate that this is a general finding and not specific to the BJ potential form.
Place, publisher, year, edition, pages
American Physical Society , 2013. Vol. 88, no 5, 052519-1-052519-9 p.
Atom and Molecular Physics and Optics
IdentifiersURN: urn:nbn:se:liu:diva-101974DOI: 10.1103/PhysRevA.88.052519ISI: 000327314400008OAI: oai:DiVA.org:liu-101974DiVA: diva2:667180
FunderSwedish Research Council, 621-2011-4249
Funding agencies|German Science Foundation|GRK 1640|German Israeli Foundation||Swedish Research Council (VR)|621-2011-4249|Linnaeus Environment at Linkoping on Nanoscale Functional Materials (LiLi-NFM)||VR||2013-11-252013-11-252013-12-28Bibliographically approved