Sylvia Serfaty, University Pierre et Marie Curie Paris VI and Courant Institute TITLE AND ABSTRACT: Crystallisation in 2D Coulomb systems. We are interested in the classical two-dimensional Coulomb gas. Zero temperature states correspond to "weighted Fekete sets", and certain particular temperature states correspond to some random matrix ensembles. We connect the problem to the "renormalized energy" W, a Coulombian interaction for an infinite set of points in the plane that we introduced with Etienne Sandier in connection to the Ginzburg-Landau model, and whose minimum is expected to be achieved by the "Abrikosov" triangular lattice. Results include a next order asymptotic expansion of the partition function, and various characterizations of the behavior of the system at the microscopic scale. When the temperature tends to zero we show that the system tends to "crystallize" to a minimizer of W. This is based on joint works with Etienne Sandier, and some with Simona Rota Nodari.