TOTAL DIFFERENTIAL CROSS-SECTIONS AND DIFFERENTIAL ENERGY-LOSS SPECTRA FOR HE-C2H2 FROM AN AB-INITIO POTENTIAL

State-to-state elastic and rotationally inelastic differential cross s ections for He + C2H2 scattering were obtained from an ab initio poten tial computed by symmetry-adapted perturbation theory (SAPT) by means of converged close-coupling calculations. From these state-resolved da ta total differential cross sections at E-cm=71.3 meV and energy loss spectra at E-cm=62.0 and 102.9 meV were determined by transformation t o the laboratory frame, and accounting for the experimental conditions via a Monte-Carlo averaging procedure, The results are in excellent a greement with experiment [U. Buck et at., J. Chem. Phys. 99, 3494 (199 3)], which proves that the SAPT potential is indeed very accurate. (C) 1997 American Institute of Physics.