Journal of Physics Condensed Matter
An analysis of the Monte Carlo diamond lattice calculation using an exact reduction relation
B. Frank, C Y Cheung
Abstract
A reduction relation is noted which allows one to relate exactly, at any temperature T, two quantities for the Ising model on the diamond lattice: (i) the ratio, essentially, of the average neighbour-neighbour correlation function and the energy per spin, P=T 2 /U 2 and (ii) a ratio of a certain pair of four-spin correlation functions Q=T4/U4. This relation is applied to Mouritsen's Monte Carlo determination of these quantities P c and Q c , at the critical point T c . It is shown that the Monte Carlo values are severely inconsistent with the exact relation. A more reliable value of the neighbour-neighbour correlation function, ( sigma 1 sigma 2 ) approximately=0.283, is calculated from the Monte Carlo data.