An attempt has been made to apply the Glasner-Tompkins relation to LiH and LiF crystals and to examine the reorientation of H and ${\mathrm{H}}_{2}$ intersitials in LiF crystal using the matrix Hartree-Fock method of ab initio theory. A finite lattice, in which the Coulomb potential in the central region closely approximates the Madelung potential in the unit cell of the host crystal, is constructed. The results emphasize the strong dependence of the difference between the exciton band and the F-center band on the halide species and suggest a mechanism by which the U band bleaches in LiF crystal. The energetically preferred orientation of ${\mathrm{H}}_{2}$ interstitials in the 〈110〉 plane supports the conclusion that the mobile ${\mathrm{H}}_{2}$ molecules, while being unable to react with isolated F centers, can react with F-center pairs (M centers) to produce the complex U centers.