  We present a new method for the generation of atmospheric turbulence phase
screens based on the frequency shift property of the Fourier transform. This
method produces low spatial frequency distortions without additional
computation time penalties associated with methods using subharmonic subgrids.
It is demonstrated that for simulations of atmospheric turbulence with finite
outer scales, the performance of our method with respect to the statistical
phase structure function of the screen meets or exceeds other methods with
respect to agreement with theory. We outline small-scale accuracy issues
associated with modelling non-Kolmogorov spectral power laws using existing
techniques, and propose a solution. For simulations of long-range propagation
through atmospheric optical turbulence, our method provides various advantages
over standard methods.
