Direct transition from isotropic to smectic-E phase

The Landau theory of phase transitions is applied to the case of a direct isotropic to smectic-E transition. The conditions for the isotropic to smectic-E transition and the stability conditions of the smectic-E phase are calculated. The coupling of the order parameters is shown to have crucial influence on the phase behavior and the order of the transition. The temperature dependence of the nonlinear dielectric effect in the isotropic phase above the isotropic to smectic-E transition is calculated. Available experimental data are consistent with our model.