The effect of departures from Ornstein—Zernike correlations on the decay rate of order-parameter fluctuations in fluids near the critical point is considered here in the framework of the Kawasaki and Ferrell theories. For reasonable forms for the correlation function, the effect of departures from Ornstein—Zernike behavior varies from 1 to 11%, which is measurable using currently available light-scattering spectroscopic techniques.

• Received 28 September 1972

DOI:https://doi.org/10.1103/PhysRevA.7.747