PHOTOIONIZATION AND PHOTOABSORPTION CROSS-SECTION CALCULATIONS IN MOLECULES - CH4, NH3, H2O, AND HF

Photoabsorption and photoionization cross sections of CH/sub 4/, NH/sub 3/, H/sub 2/O, and HF have been calculated by using extended L/sup 2/ basis sets. The continuous spectrum results were obtained via a Stieltjes imaging procedure applied to the discretized excitation spectrum yielded by the random phase approximation, RPA. The basis sets included functions of all centered upon the heavy atom and the RPA calculations were performed both in the independent channels and in the interacting channels schemes.