Defect-freezing and defect-unbinding in the vector complex Ginzburg-Landauequation

We describe the dynamical behavior found in numerical solutions of the Vect or Complex Ginzburg-Landau equation in parameter values where plane waves a re stable. Topological defects in the system are responsible for a rich beh avior. At low coupling between the vector components, a frozen phase is fou nd, whereas a gas-like phase appears at higher coupling. The transition is a consequence of a defect unbinding phenomena. Entropy functions display a characteristic behavior around the transition. (C) 1999 Published by Elsevi er Science B.V. All rights reserved.