Ab Initio study of KN

摘要

The potential energy curves for the lowest ~3sum~-, ~3PI, and ~5sum~- states of the KN molecule have been calculated by the multireference singles and doubles configuration interaction method, including Davidson's corrections for quadruple excitations [MRCI(+Q)]. It is shown that the former two are bound, while the last one is repulsive. The electronic ground state of KN is predicted as ~3sum~- state, although the term energy of the ~3PI state is very small, 177.3 cm~(-1). The binding energy for the ~3sum~-, state is evaluated as 0.838 eV, the rotational constant B0 as 0.250 63 cm~(-1), and harmonic frequency as 324.4 cm~(-1). The spin-orbit coupling effects between the ~3PI, and ~3PI states of KN are evaluated and discussed. The same MRCI(+Q) computational procedures are applied to the isovalent LiN, KC, KO, and KCl to confirm the accuracy of present calculations. Theoretical spectroscopic constants presented here will inspire experimental studies of KN.