Petra Schmidt

Physikalisches Institut der Universität Bonn
Nußallee 12
D-53115 Bonn
Federal Republic of Germany

Office:	AVZ-I, Room 103
Phone:	+49-228-73-3724
Fax:	+49-228-73-3223
Email:	schmidt@th.physik.uni-bonn.de

Research project

The dynamical mean-field theory is extended to study the Hubbard model on a hypercubic lattice in infinite dimensions in the presence of a time-dependent external field. The Keldysh-Green's function formalism is employed to handle this nonequilibrium problem. Using the Floquet theorem, it is shown that the local Green's function and the self-energy are matrices in the energy-sidebands due to quasi-energy conservation modulo the external frequency. A closed set of self-consistency equations is derived in the case of a driving field with a small but finite wave vector. For a uniform field, this problem is solved numerically using iterated perturbation theory. The local frequency-dependent Green's function and the self-energy are obtained for different values of the field amplitude. An effective spectral density and an effective distribution function are defined in the nonequilibrium case. The iterated-perturbation results show, that the sidebands become more relevant with increasing strength of the external field. In addition, the frequency-dependent optical conductivity of the Hubbard model with a driving external field is derived.

Publications

P. Schmidt
Time-dependent dynamical mean-field theory
Diploma thesis, December 1999

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Last modified: Mon Jul 26 10:04:01 MET DST 1999