EXCITONIC MOLECULE IN CUCL CRYSTAL

The electronic structure of a biexciton is discussed while taking into account the detailed band structure of CuCl. The fine structure of th e excitonic molecule is clarified with the effective electron-hole exc hange effect taken into account beyond the effective mass approximatio n. The electron-hole exchange interaction mixes the states of opposite parities with respect to the permutation of electrons and holes. Two trial envelope functions, symmetric and antisymmetric under the permut ation of two electrons or two holes, were used in the numerical minimi zation of the ground state energy of the biexciton. The obtained bindi ng energy of the biexciton, as well as, the ratio of the mixing of the trial envelope functions of opposite parities are presented.