Inelastic Helium Atom Scattering from the Commensurate Monolayer Solid H$_2$/NaCl(001)

A calculation of inelastic low energy helium atomic scattering by a monolayer with one-phonon creation\footnote{F. Y. Hansen and L. W. Bruch, J. Chem. Phys. {\bf 127}, 204708 (2007)} is reported for the dilated quantum monolayer solid H$_2$/NaCl(001). The shear horizontal phonon mode again is accessed for small misalignment of the scattering plane relative to the monolayer axes. Qualitative agreement for the systematic trends in the inelastic scattering experiments\footnote{F. Traeger and J. P. Toennies, J. Phys. Chem. B {\bf 108}, 14710 (2004)} is achieved. Two monolayer phonon branches are identified. The role of the Debye-Waller attenuation in diffraction intensities is discussed.