On liquid crystal phase transitions between isotropic and nematic phase states Changyou Wang Purdue University In this talk, I will consider asymptotic behavior of minimizers Qϵ , as the parameter ϵ→0, of the Landau- de Gennes energy ELdG(Q)=∫Ω(fe(∇Q)+1ϵ2fb(Q))dx, Ω⊂R3, for uniaxial nematic liquid crystals Q, where the bulk energy density function fb(Q) has two minimal wells at isotropic phase Q=0 and nematic phase Q=s+(n⊗n−1/3I). We will discuss the limit value of ELdG(Qϵ) in terms of the area of the sharp interface S between the two phases, which is an area minimizing surface, and the 1d-minimal connecting energy c0 between the two phases. We will also discuss the limiting behavior of Qϵ in term of minimizing configurations of the Oseen-Frank energy functional, including a surface energy from S. This is a joint work with Yuanzhen Shao from Purdue University.