Shape parameters and uniaxial deformability of mesogenic dimers with flexible spacers

We introduce a set of statistical shape parameters that quantify the concep t of the "average shape" of flexible molecules in isotropic and in nematic media. These shape parameters are obtained as conformational averages of ge ometrical tensors constructed from the relative positions and orientations of the sub-molecular units. The deformability of the average molecular shap e is quantified in terms of the variation of the respective shape parameter s under the action of an ordering field. The quantification of shape and de formability is applied to the description of dimers consisting of two rod-l ike mesogenic units connected by an alkyl spacer.