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 beta14. 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.