THE SINGLET TRIPLET ENERGY SEPARATIONS OF GECL2, GEBR2, GEL2, GEHCL, GE-HBR, AND GEHI

The singlet-triplet energy separations of GeCl2, GeBr2, GeI2, GeHCl, GeHBr, and GeHI were obtained using the complete-active-space multiconfiguration self-consistent-field (CAS-MCSCF) method followed by multireference configuration interaction (MRCI). We also studied the effect of spin-orbit coupling on the heaver GeI2 using the relativistic CI (RCI) method. In addition to the 1A1 ground state we found B-3(1) and B-1(1) excited states for GeCl2, GeBr2, and GeI2. The X 1A1-A B-3(1) calculated energy splittings are 60.3 kcal/mol for GeCl2, 55.5 kcal/mol for GeBr2, and 42.4 kcal/mol for GeI2. The ground-state properties for GeCl2 are R(e) = 2.191 angstrom, THETA(e) = 100.5-degrees, and mu(e) = 2.956 D. The corresponding value for GeBr2 are R(e) = 2.373 angstrom, THETA(e) = 101.8-degrees, and mu(e) = 2.394 D, while our computed constants for GeI2 are R(e) = 2.574 angstrom, THETA(e) = 102.8-degrees, and mu(e) = 1.422 D. For GeHCl, GeHBr, and GeHI molecules we computed the properties of the 1A' ground state and 3A" and 1A" excited states. The X 1A'-A3A" energy splittings are computed as 39.9 kcal/mol for GeHCl, 37.9 kcal/mol for GeHBr, and 34.8 kcal/mol for GeHI. The spectroscopic properties for 1A' state are R(e)(Ge-H) = 1.589 angstrom, R(e)(Ge-Cl) = 2.201 angstrom, THETA(e) = 94.3-degrees, and mu(e) = 2.553 D for GeHCl, R(e)(Ge-H) = 1.572 angstrom, R(e)(Ge-Br) = 2.388 angstrom, THETA(e) = 93.9-degrees, and mu(e) = 2.341 D for GeHBr, and R(e)(Ge-H) = 1.575 angstrom, R(e)(Ge-I) = 2.580 angstrom, THETA(e) = 93.5-degrees, and mu(e) = 1.947 D for GeHI.