High-temperature study of the Kosterlitz-Thouless phase transition in the XY model on the triangular lattice.

High temperature series expansions of the spin-spin correlation function for the XY (or plane rotator) model on the triangular lattice are extended by two terms up to order β 14. Tables of the expansion coefficients are reported for the correlation function spherical moments of order l = 0 and 2. Our analysis of the series supports the Kosterlitz-Thouless predictions on the structure of the critical singularities and leads to fairly accurate estimates of the critical parameters.