THE SMA[--]SMC-ASTERISK (SMC) PHASE-TRANSITION IN A PLANAR CELL WITH A POLAR SURFACE COUPLING

The phase transition from the SmA to the lower-temperature SmC or SmC phase in a restricted geometry of a planar cell is studied theoretica lly, considering a polar coupling of the ferroelectric liquid crystal to the surfaces. The lambda-line in a (2L, T) phase diagram, where T i s the temperature and 2L is the cell thickness, is determined numerica lly. The critical temperature T-c of the SmA <-> SmC (SmC) phase tran sition exibits nonmonotonic dependence on the cell thickness 2L. Two t ricritical points are found on the lambda-line, which could be candida tes for the Lifshitz points.