Kirkwood-Salsburg expansion

The idea for the potential distribution theorem, and consequently the Mayer-Montroll expansion Eq. (6.3), is to consider a distinguished, additional molecule. The idea for the Kirkwood-Salsburg expansion is to consider a distinguished, additional, p h atom conditional upon the locations of (p — 1) others. We will consider the p = 2 case specifically. 

Aside from potential utility as generators of approximate physical theories for giy (r, r ), these Kirkwood-Salsburg expansions permit systematic construction of... 

The Mayer-Montroll (Mayer and Montroll, 1941) and Kirkwood-Salsburg (Kirkwood and Salsburg, 1953) expansions are storied parts of basic statistical thermodynamics (Stell, 1985), but have been neglected for practical purposes because of a lack of recognition of how simple and simplifying they can be. 

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