Collision-induced absorption by ${\mathrm{H}}_2$-He pairs in the fundamental band: Rotational states dependence

Previously, we have computed the induced-dipole-moment surface of collisional ${\mathrm{H}}_2$-He complexes from first principles using highly correlated wave functions. These data were used to calculate the collision-induced absorption spectrum of the fundamental band [L. Frommhold and W. Meyer, Phys. Rev. A 35, 632 (1987)]. The present study examines the dependence of radial induced-dipole transition moments and the associated spectra on the rotational states involved, a dependence that was suppressed in the previous study. Whereas the neglect of the rotational quantum numbers j,j’ of the initial and final state of ${\mathrm{H}}_2$ is justified for the purely rototranslational spectra of ${\mathrm{H}}_2$-He, we find significant variations with j,j’ of the radial induced-dipole transition elements and the induced spectra for the fundamental band of ${\mathrm{H}}_2$. Similar effects are expected for other molecular bands and systems of interest, especially those involving hydrogen molecules.