THEORETICAL DETERMINATION OF THE $Na_{2}~ A^{1}\Sigma^{+}_{u} \rightarrow X^{1}\Sigma^{+}_{g}$ TRANSITION MOMENT AND LIFETIMES

Author Institution: National Bureau of Standards; Chemistry Division, Argonne National LaboratoryMulticonfiguration self-consistent-field (MCSCF) calculations have been carried out on the $X^{1}\Sigma^{+}_{g}$ and $A^{1}\Sigma^{+}_{u}$ states of $Na_{2}$. The calculated potential energy curves are in good agreement with the experimental RKR curves of Hessel and Kusch. The $A \rightarrow X$ transition moment has been calculated as a function of nuclear separation using the MCSCF wavefunctions. A least squares fit to a cubic polynomial provides an analytic representation that is accurate to within 0.1 debye between 4.5 and 12.0 bohrs. The expansion coefficients are $C_{0} = 0.75784, C_{1} = 2.11363, C_{2} = - 0.10619, C_{3} = - 0.00079$, where $\mu$ is in debyes and the nuclear separation is in bhors (1 bohr = 5.291772 nm). Lifetimes for the $A \rightarrow X$ transition have been calculated using the theoretical transition moment and the experimental potential curves of Hessel and Kusch