Close-coupled and coupled-states calculation of shear viscosity SBE cross sections for the H2–He system

Abstract

Close‐coupled (CC) and coupled‐state (CS) calculations of kinetic theory relaxation and production cross sections are presented for the system H₂ at infinite dilution in a bath of He. Performing these calculations for the same potential has allowed a test to be made of the efficacy of the CS procedure for use in calculating kinetic theory cross sections, especially those determining the Senftleben–Beenakker effects (SBE) in transport phenomena. The CS procedure is found to work extremely well (better than 1% agreement with CC results) for those cross sections that are predominantly elastic, to work rather well for relaxation cross sections determined either by reorientation of energetically inelastic collisonal events (about 10% agreement with CC results), and to work relatively poorly for production cross sections. In fact, the CS procedure for light molecules fares only marginally better than the IOS procedure for heavier molecules in the calculation of production cross sections. Finally, using only CC results, the sensitivity of the shear viscosity SBE is shown to be sufficient to distinguish easily between two recently obtained ab initio potentials for the H₂–He system.