Order-Parameter Correlations within the Screening Approximation

A central problem in the theory of phase transitions is the calculation of the order-parameter correlation function. Here we study the correlation function of an n-component order parameter whose configuration energy is determined by the usual Landau functional. Using a screening approximation, we obtain a simple closed form for the Fourier transform of the correlation function and examine its dependence on wave vector →k and the reciprocal correlation length k.