Potential energy surfaces for insertion of hafnium atoms into hydrogen

Kalyan K. Das, K. Balasubramanian
1991 The Journal of Physical Chemistry  
3979 kt = 1 -3(1a)2/3 + 2(1 -a ) Acknowledgment. This research was supported in part by grants from the National Science Foundation (MSM 86-17850) and the Texas Higher Education Coordinating Board, Advanced Technology Program. We also thank H. J. Arnott for access to the SEM/EDX instrumentation. Complete active space multiconfiguration self-consistent field (CAS-MCSCF) followed by second-order CI (SOCI) and relativistic CI (RCI) calculations including spin-orbit coupling are carried out on
more » ... carried out on low-lying electronic states of HfH,. Potential energy surfaces of 12 electronic states of HfH2 for studying the insertion of Hf(a3F), Hf(a'D), and Hf(aSF) states into H2 are constructed. We find that the low-lying Hf('D) inserts into H2 spontaneously to form the HfH2 molecule in the 'A, state, while the 3F ground state of Hf atom has to surmount a barrier for insertion into H2. However, the small but nonnegligible spin-orbit coupling matrix elements at the crossing of the 'Al bent-structure surface with triplet surfaces provides a nonzero nonadiabatic transition probability for insertion of the Hf(a3F) state with a smaller barrier into H2. The 'A, ground state of HfH2 was found to have re = 1.842 A, 8, = 126.7", p, = 0.31 D, and 0, = 30 kcal/mol relative to Hf(3F2) + H2. There are several low-lying triplet and singlet states that mix with each other in the presence of spin-orbit coupling. (1) Martinho, J. A.; Beauchamp, J. L.
doi:10.1021/j100163a018 fatcat:4jrbtcgvuzbmxapwlf56hamslu