Geometric Phase Approach to Dielectricity Based on the Born-Oppenheimer Approximation

Macroscopic polarization differences in crystal dielectrics have been accurately treated by certain authors using the geometric phase approach. However, in their treatments the explicit meaning of the slowly varying parameters was not explored. In this paper we restudy the problem under the Born-Oppenheimer approximation. It turns out that the coordinates of nuclei in the system can be taken as the slowly varying parameters. In addition, our treatment is no longer restricted to the case of null electric field.