MRCISD calculations of the six lowest valence states of I-2(-)

Potential curves for the four Hund's case (a) basis electronic states ((2)S igma(u)(+), (2)Pi(g), (2)Pi(u), and (2)Sigma(g)(+)) correlating with the I( P-2(u)) + I-(S-1(g)) dissociation limit have been calculated at the MRCISD level of theory using an all-electron double-zeta basis set augmented with an extensive set of polarization and diffuse functions complete through i a ngular momentum functions. Transition moments for the dipole allowed transi tions between these states are determined as a function of internuclear sep aration. The four Hund's case (a) curves are used to determine the six Hund 's case (c) potential curves which arise when spin-orbit coupling is consid ered. The rovibrational eigenvalues for each of these six states are determ ined numerically, and standard spectroscopic constants are determined by fi tting the energy of these levels to a Duham series. The results are compare d with available experimental and theoretical information.