  Using tools of nonequilibirum mechanics, we study a model of self-propelled
hard rods on a substrate in two dimensions to quantify the interplay of
self-propulsion and excluded-volume effects. We derive of a Smoluchowski
equation for the configurational probability density of self-propelled rods
that contains several modifications as compared to the familiar Smoluchowski
equation for thermal rods. As a side-product of our work, we also present a
purely dynamical derivation of the Onsager form of the mean field excluded
volume interaction among thermal hard rods.
