Ab initio model calculations to treat electron scattering from polar polyatomic targets: H₂S and NH₃

A parameter-free modelling of the exchange and correlation-polarization forces which play a fundamental role in describing the scattering of slow electrons from molecular targets is applied here to the calculation of total integral cross sections and differential cross sections for electron collisions with polyatomic targets: H 2 S and NH 3 . Several features of the results are discussed and analysed to try and shed more light on the physical details of the processes at hand. The present computation constitutes one of the first examples of such an analysis for the systems and appears to provide, among other things, much original information on the possible existence of low-energy, metastable negative ions of NH 3 and H 2 S in their ground electronic states.