Fyzikální ústav Akademie věd ČR

Seminar Tuesday, 24/04/2012 15:00 - 16:00

Speakers: Vladislav Pokorný (Dept. of condensed matter theory, Institute of Physics ASCR, Prague)
Place: Na Slovance, přednáškový sál v přízemí
Presented in English
Organisers: Department of Condensed Matter Theory

Abstract: Coherent potential approximation (CPA) is a theory successfully describing one-particle properties of disordered electronic systems. However, it misses quantum coherence of a correlated particle propagation. Vertex corrections to the electrical conductivity due to the symmetry of the two-particle vertex vanish in this approximation. We introduce a computational scheme for the leading-order vertex corrections to the Drude electrical conductivity. It is based on a systematic expansion around the mean-field (CPA) solution via the limit to high spatial dimensions. Moreover, we show how to adopt this expansion so that the electrical conductivity with vertex corrections remain nonnegative for any disorder strength. Further on, we demonstrate that the sign of the leading vertex corrections is always negative for all types of elastic scatterings, static or thermally equilibrated. Explicit calculations are done for the disordered Anderson model and pure and disordered Falicov-Kimball models.