High-temperature series for classical n-vector models with general anisotropy

A compact parametrization is derived for the high-temperature series expansions of the free energy and two-spin correlation function of classical n-vector models with completely general anisotropic pair interactions. The number of independent coefficients needed for general anisotropy is much less than required in conventional expansions. The series for the free energy of the Heisenberg model (n=3) on three cubic lattices is presented to tenth order as an example.