Abstract
A simple model is found for the anomalous density dependence of electron mobilities by applying the energy shift and broadening of multiple scattering theory plus the uncertainty principle to the transport equations. The shift alone when properly applied immediately predicts the observed positive and negative effects in Ar. The exponential decrease observed in H2, CO2, and He is found to result from a combination of their negative energy shift plus the broadening, which together push the electron distribution function down to localised negative energy states. Possible application of the model to amorphous semiconductors is also discussed.