Ab initio calculations of doubly resonant sum-frequency generation second-order polarizabilities of LiH

In the present Letter doubly resonant sum-frequency generation (DR-SFG) second-order polarizabilities (β) are reported for the lithium hydride molecule. The calculations, which refer to the diagonal longitudinal component of β and ignore rotation, are based on data evaluated using the multireference configuration interaction method with singles and doubles. The DR-SFG results are partitioned into their infrared–visible and visible–infrared components. They are analyzed as a function of the infrared and visible frequencies as well as the number of vibrational states considered in the sum-over-states expressions.