## Abstract

We consider the conditions on the triplet-distribution function g ^{(3)}, and the pair-distribution g^{(2)}, sufficient that thermodynamic quantities calculated from g^{(2)} be state functions. We show that g^{(3)} cannot be, even to first order in density, equivalent to the Kirkwood superposition approximation. We obtain a g^{(3)} that does yield a thermodynamically self-consistent g^{(2)}, to second order in density. We show that this g^{(2)} differs little from the exact g^{(2)}, at that order. We also examine the low-density behavior of a partially self-consistent closure in which angular correlations appear explicitly. The latter closure is found to describe three-particle correlations well when two of the particles are in contact. A principal conclusion which follows from these studies is that the criterion of thermodynamic self-consistency is useful as a constraint in constructing closures, although it does not in itself determine a closure.

Original language | English (US) |
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Pages (from-to) | 4257-4263 |

Number of pages | 7 |

Journal | The Journal of chemical physics |

Volume | 82 |

Issue number | 9 |

DOIs | |

State | Published - Jan 1 1985 |