  The influence of optical scattering and thermal radiation models an the
Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect is studied. Lambertian
formulation is compared with Hapke scattering and emission laws and
Lommel-Seeliger reflection. Although the form of reflectivity function strongly
influences mean torques due to scattering or thermal radiation alone, their
combined contribution to the rotation period YORP is not much different from
the standard Lambertian values. For higher albedo values the differences
between the Hapke and Lambert models become significant for the YORP in
attitude.
