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 $\delta L_j$ and $\delta G$ 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 $\delta L_j$ and $\delta G$. Change $\delta G$ and dependence $G(S)$ in the $B$ phase are related to change in the conformation (flattening) of aromatic molecular cores.