Question

What is Landau-deGenes Expansion?

Answer 1

The Landau theory of phase transitions is based on the idea that the free energy can be expanded as a power series in the order parameter

For a second order phase transition, the order parameter grows continuously from zero at the phase transition so the first few terms of the power series will dominate.

Answer 2

Landau degenes expansion in physics is a theory that Lev Landau introduced in a attempt to formulate a general theory of continuous.