SEMINAIRE MERCREDI 14 MAI 2008
14 heures
Salle Séminaire 4
Attention lieu inhabituel: en amphi 4!!!
Centre de Physique Théorique
Marseille-Luminy

Horia Cornean
Department of Mathematical Sciences, Aalborg University
Fredrik Bajers Vej 7G
9220 Aalborg, DENMARK
people.math.aau.dk/~cornean

Title: Optimally localized Wannier functions for quasi
one-dimensional nonperiodic insulators

Abstract: It is proved that for general, not necessarily periodic quasi
one dimensional systems, the band position operator corresponding to
an isolated part of the energy spectrum has discrete spectrum and its
eigenfunctions have the same spatial localization as the corresponding
spectral projection. As a consequence, an eigenbasis of the band
position operator provides a basis of optimally localized
(generalized) Wannier functions for quasi one dimensional systems,
thus proving the strong conjecture of Marzari and Vanderbilt. If the
system has some translation symmetries (e.g. usual translations, screw
transformations), they are inherited by the Wannier basis. This is
joint work with A. Nenciu and G. Nenciu.