Exact Statistical Mechanics of a One-Dimensional System with Coulomb Forces. II. The Method of Functional Integration

Abstract

The statistical mechanics of a one‐dimensional system of charged sheets is studied in the formalism of the grand canonical ensemble. It is shown that the grand partition function may be expressed as a Wiener integral, i. e., as an average of a certain functional of Brownian motion paths. This functional integral is then expressed in terms of the fundamental solution of a partial differential equation of diffusion type. This depends on a theorem of Kac whose proof is also given. The generality of this method is discussed. When all charges are integral multiples of a common unit the problem is reduced to the determination of the largest characteristic value of an ordinary differential operator with periodic coefficients. An invariance property of the thermodynamic potential is shown to imply charge neutrality in the infinite system limit. A theorem is proven which, in certain cases, excludes the possibility of a thermodynamicphase transition. The method is generalized to yield exact expressions for the n‐particle reduced density functions. Some properties of the two‐particle functions are discussed.