Topological transition in a two-dimensional model of liquid crystal
  Simulations of nematic-isotropic transition of liquid crystals in two dimensions are performed using an O(2) vector model characterised by non linear nearest neighbour spin interaction governed by the fourth Legendre polynomial $P\_4$. The system is studied through standard Finite-Size Scaling and conformal rescaling of density profiles of correlation functions. A topological transition between a paramagnetic phase at high temperature and a critical phase at low temperature is observed. The low temperature limit is discussed in the spin wave approximation and confirms the numerical results. 
Ana Fari\~nas-Sanchez (IVIC), Ricardo Paredes (IVIC), Bertrand Berche   (IVIC, LPM)