The appropriate averages are taken in the canonical ensemble ( N , V , T ) , with Z N = ∫ ∫ ⋯ ⋯ ∫ ∫ e − − β β U N d r 1 ⋯ ⋯ d r N the configurational integral, taken over all possible combinations of particle positions. The probability of an elementary configuration, namely finding particle 1 in d r 1 , particle 2 in d r 2 , etc. is given by