Discrete Variational X_α Cluster Calculations of Electronic Structure for the ReH₉^2- Anion and Its Crystal K₂ReH₉

Electronic structures for ReH₉^2- anion and its crystal K₂ReH₉ have been calculated using the DV-X_α cluster method. Two different basis sets with and without the 6p atomic orbitals of Re atom have been adopted in the calculations. Results show that the Re-H bond mainly consists of Re 5d atomic orbitals and ls orbital of the ligand hydrogen atoms. Contribution from 6s and empty 6p atomic orbitals for rherium atom to the bonded molecular orbitals of this anion is little or nothing. Thus, the Re5d-H1s interaction is a characteristics of the Re-H bond in the ReH₉^2- anion. An anion of ReH₉^2- is embeded into a larger cluster with a empty rigion to simulate the long-range coulombic potential in the ionic crystal. The calculated band gap is decreased. The electronic spectroscopy of the K₂ReH₉ crystal has been reasonably interpreted.