Successes and failures of Kadanoff-Baym dynamics in Hubbard nanoclusters

Marc Puig von Friesen

Thursday, 13 November 2008, 11:15
Seminar room F

We study the effect of a time-dependent external field on small, strongly correlated clusters, described by a Hubbard Hamiltonian, by propagating the Kadanoff-Baym equations within the 2nd Born, GW and the T-matrix approximations and comparing these results to those of the exact solution. We observe that the T-matrix is far superior to the GW approximation and slightly better than the 2nd Born. In the long time limit we achive an unphysical steady state which we attribute to the implicit inclusion of infinite order diagrams in a few-body system.