New features of a smectic-A-crystal-B phase transition in a homologous series of liquid crystals

The components L j of the Lorentz tensor and the polarizability density of molecules G in the smectic- A and crystalline- B phases have been determined for homologues of the series of alkyl- p -(4-alkoxybenzylideneamino-)cinnamates. The quantity L j ( G ) in both phases is a linear (quadratic) function of the orientational order parameter of molecules S , which is invariant (noninvariant) with respect to the A - B transition, which is manifested in the form of jumps δ L j and δ G and enhancement of the G ( S ) dependence. An increase in the length of terminal molecular chains and weakening of interlayer correlation of molecules are accompanied by strengthening of the A - B transition of the first order and G ( S ) dependences in both phases together with an increase in δ L j and δ G . Change δ G and dependence G ( S ) in the B phase are related to change in the conformation (flattening) of aromatic molecular cores.