QUANTUM AND SEMICLASSICAL CALCULATIONS OF H-2-HE VIBRATIONAL LINE-SHAPE PARAMETERS AT HIGH-TEMPERATURE

Quantum close-coupling (CC) and semiclassical (SC) calculations of bro adening and shifting coefficients of Q(j) rovibrational lines have bee n performed using an nb initio potential energy surface. The agreement between the theoretical results and experimental data available up to 1000 K is very good for the broadening coefficient gamma and reasonab le for the shift delta. The main interest is to test the validity of t he semiclassical method versus CC calculation on a wide range of tempe rature to allow confident application of the SC method to more complex systems. The agreement is very satisfactory. Further the SC model per mits a detailed analysis of the mechanisms involved in the temperature dependence of the molecular parameters gamma and delta. (C) 1997 Amer ican Institute of Physics.