Non-equilibrium critical dynamics of the two-dimensional XY model with Hamiltonian equations of motion

Non- equilibrium critical dynamics of the two- dimensional XY model is investigated with Hamiltonian equations of motion. Critical relaxation starting from both ordered and random states is carefully analyzed, and the short-time dynamic scaling behavior is revealed. Logarithmic corrections to scaling are detected for relaxation with a random initial state, while power- law corrections to scaling are observed for relaxation with an ordered initial state. The static exponent. and dynamic exponent z are determined around and below the Kosterlitz - Thouless phase transition temperature. Our results show that the deterministic dynamics described by Hamiltonian equations is in the same universality class as the stochastic dynamics described by Monte Carlo algorithms and Langevin equations.