STUDIES ON THE ENERGY-BAND STRUCTURES AND CHEMICAL-BOND PROPERTIES OFLAX(X=N, P, AS, SB) CRYSTALS

The energy band structures of LaX(X=N, P, As, Sb) crystals have been s tudied by using LMTO-ASA method. The calculated energy gaps of these c rystals are 2. 30 eV for LaN, 2. 05 eV for LaP, 1. 66 eV for LaAs and 1. 34 eV for LaSb. The results are in good agreement with experimental data, At the same time, using these calculated results of energy band structures of these crystals, the chemical bond properties have been analyzed and calculated, The covalency values of these crystals are 26 .15% for LaN, 32.54% for LaP, 33.30% for LaAs and 36.49% for LaSb, whi ch agree satisfactorily with the calculated ones by using PV (Phillips -Vechten) theory.