ABSTRACT

The modern approach towards an understanding of phase transition begins with Landau theory. Although largely phenomenological, it provides the conceptual framework that is the basis of nearly all theories and most discussions of phase transitions. At the heart of the theory is a simple Taylor expansion of free energy in terms of order parameters. This has been introduced in the previous chapter (Chapter 16). The Landau theory is often termed as a mean field theory that is equivalent to stating that intermolecular correlations are averaged over space. So, some of the predictions are not quantitatively correct. But the main merit and strength of the Landau theory is its generality that comes with a simplicity that is unmatched in theoretical discussions.