December 7, 2010 11:00

In recent years there is a renewed interest in systems where multiple degenerate (or not degenerate) bands are "close" to the Fermi level. In such systems the effective interbands terms leads to topological properties of the effective intraband position or momentumoperators; these properties are charaterized by the so called intraband Berry curvature whichplays the role of an effective k-space magnetic field. In thistalk we review these "topological" properties of multibandssystems. In particular we show how the usual semiclassicalequation of motion in external electric and/or magnetic fieldare modified in the presence of Berry curvature in two ways:there appears so called anomalous velocity and the anomalousmagnetization term. We also discuss the importance of theseBerry curvature on for some linear and bilinear response functions.