TRANSITION-PROBABILITY AND PHOTOIONISATION CROSS-SECTION CALCULATIONS FOR CH4 AND HF BY ONE-CENTER EXPANSION AND STIELTJES TECHNIQUE

Transition probabilities, partial and total photoionisation cross sections for CH4 and HF are obtained from a discrete basis set calculation by using the Stieltjes imaging technique for the continuum oscillator strength densities. Bound and continuum electronic eigenfunctions in the ground-state equilibrium geometry are described in the independent channel approximation using large basis sets of integrable functions centred on the heavy atom. Besides the usual STO functions, hydrogenic Rydberg functions and diffuse oscillatory functions are used to improve the description of the bound excited orbitals and the continuum orbitals respectively. The results in the discrete and continuous energy regions compare well with the available experimental data, confirming the validity of the approach for this class of molecules.