Free energy landscape approach to glass transition

As a Landau-type theory for the glass transition, we present a free energy landscape (FEL) picture which provides a unified understanding of glass transition singularities and show that the FEL can really be calculated by a theoretical and a computational approach. We first give a clear definition of the FEL and argue that there are two kinds of cooperative rearranging region. One is the region defined by the difference between two adjacent basins which could be called simultaneously rearranged region and the other is the atoms involved in the excited state between two adjacent basins. Exploiting the density functional theory, we obtain the FEL for a relaxation process which is characterized by a string motion and determine the size of the cooperatively rearranging region. We also show that the FEL can be determined by the principal component analysis for time dependent configuration obtained by the MD simulation.