In the present calculation we used the effective mass Hamiltonian (4, 5)H is the 4x4 matrix given by (1, 5) with the constant I ? = 2.75 and 6 = 0.84 deduced from (6, 7). The unit of energy is E = e / 4 2 IAI = 2.15 meV and unit of length Lo = 2adAl /e = 210 8 , X = 15.9 is the static dielectric constant.