The problem of identifying which molecular features of liquid crystals influence the formation of nematic and smectic phases is complex, Extensive simulation studies of steric and electric systems of thermotropic liquid crystals have had considerable success in simulating liquid crystal phase behaviour employing a variety of hard, soft and realistic models. We report here some links between molecular design of real liquid crystal molecules, using molecular properties calculated from semiempirical quantum techniques and the results of a series of simulation studies of steric and electric molecular asymmetry. The simulation studies allow electric and steric molecular properties to be considered separately, thus illuminating the effect of each.