The anomalous velocity term in the semiclassical model of a Bloch electron
deviates the trajectory from the conventional one. When the Berry curvature
(alias noncommutative parameter) is a monopole in momentum space as found
recently in some ferromagnetic semiconductors while observing the anomalous
Hall effect, we get a transverse shift, similar to that in the optical Hall
effect.Comment: 4 pages. A figure added. To be published in Phys. Lett.