Abstract
The crystalline family Sn2P2(Sex S1-x)6 presents particularly interesting features due to its low symmetry. The direction of polarization is thus not symmetry fixed, neither in the ferroelectric, nor in the incommensurate phase. We analyze the situation close to the inc transition, close to, and at the lock-in transition: we use a Landau-Ginzburg functional the minimization of which allows to get results on the polarization rotation as a function of temperature.