ENERGY-BANDS AND CHEMICAL BONDING IN THE NOVEL HYDRIDE NITRIDES SR-2(H)N AND BA-2(H)N

We have studied the electronic structure and chemical bonding of the n ovel ternary hydride nitrides Sr-2(H)N and Ba-2(H)N by means of densit y functional theory. In these insulating materials the hydrogen atom i s found to be close to an H- anion state, while there is considerable covalency in the metal-nitrogen bond, which reduces the effective N ch arge to approximate to - 1.8. To resolve a discrepancy with experiment al data concerning the nature of the optical gap in Sr-2(H)N we have a lso calculated the energy bands of the imide Sr(NH). In addition, we h ave simulated, in a rough model, the imide formation in these hydride nitrides, which occurs when the materials are illuminated with light. (C) 1998 Elsevier Science Ltd. AII rights reserved.