Dresden 2006 – scientific programme
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MM: Metall- und Materialphysik
MM 22: Electronic Properties II
MM 22.2: Talk
Wednesday, March 29, 2006, 14:15–14:30, IFW A
The fundamental gap in reduced-density-matrix-functional theory — •N. Helbig1, N.N. Lathiotakis1, M. Albrecht2, and E. K. U. Gross1 — 1Freie Universität Berlin, Arnimallee 14, 14195 Berlin — 2Theoretical Chemistry FB 08, University of Siegen, 57068 Siegen
We present a novel method for calculating the fundamental gap. To this end, reduced-density-matrix-functional theory is generalized to fractional particle number. For each fixed particle number, M, the total energy is minimized with respect to the natural orbitals and their occupation numbers. This leads to a function, EtotM, whose derivative with respect to the particle number has a discontinuity identical to the gap. In contrast to density functional theory, the energy minimum is generally not a stationary point of the total-energy functional. Numerical results are presented for alkali atoms, for small molecules and ionic periodic systems.
[1] N. Helbig, N.N. Lathiotakis, M. Albrecht, E.K.U. Gross, cond-mat/0504436