  This work develops a new generalized technique for determining the static and
dynamic properties of any non-collinear magnetic system. By rotating the spin
operators into the local spin reference frame, we evaluate the zeroth, first,
and second order terms in a Holstein-Primakoff expansion, and through a Green's
functions approach, we determine the structure factor intensities for the
spin-wave frequencies. To demonstrate this technique, we examine the spin-wave
dynamics of the generalized Villain model with a varying interchain
interaction. The new interchain coupling expands the overall phase diagram with
the realization of two non-equivalent canted spin configurations. The
rotational Holstein-Primakoff expansion provides both analytical and numerical
results for the spin dynamics and intensities of these phases.
