POTENTIAL-ENERGY SURFACES FOR INSERTION OF ZR INTO H-2

Potential energy surfaces of twelve electronic States of ZrH2 are constructed using a complete active space self-consistent field method (CASSCF) followed by mult-reference singles + doubles configuration interaction (MRSDCI) cal- culations. The Zr(3F) ground state of zirconium atom has to surmount a barrier of llkcal/mole for insertion into H2. The excited Zr(1D) state inserts into H2 almost spontaneously. The excited Zr(5F) atom forms a weak complex with H2 and subsequently has to surmount a large barrier for insertion into H2. Three possible nearly-degenerate bent electronic States are found for ZrH2 (1A13B1 and3A1). The1Al ground state of ZrH2 was found to be 26kcal/mole more stable compared to Zr(3F) + H2. Mulliken population analyses reveal considerable Ad5s5p hybridization of the metal atom in the Zr-H bonds. The dipole moments of bent low-lying electronic States reveal that the ZrH bonds are ionic with Zr+H− polarity. The effects of ten-component 4/-type functions are also studied on the various electronic States of ZrH2. © 1990 Taylor & Francis Group, LLC.