### Abstract

Two complementary routes to a new integral equation theory for site-site molecular fluids are presented. First, a simple approximation to a subset of the atomic site bridge functions in the diagrammatically proper integral equation theory is presented. This in turn leads to a form analogous to the reactive fluid theory, in which the normalization of the intramolecular distribution function and the value of the off-diagonal elements in the density matrix of the proper integral equations are the means of propagating the bridge function approximation. Second, a derivation from a topological expansion of a model for the single-site activity followed by a topological reduction and low-order truncation is given. This leads to an approximate numerical value for the new density coefficient. The resulting equations give a substantial improvement over the standard construction as shown with a series of simple diatomic model calculations.

Original language | English (US) |
---|---|

Article number | 204512 |

Journal | Journal of Chemical Physics |

Volume | 123 |

Issue number | 20 |

DOIs | |

State | Published - 2005 |

Externally published | Yes |

### Fingerprint

### ASJC Scopus subject areas

- Atomic and Molecular Physics, and Optics

### Cite this

*Journal of Chemical Physics*,

*123*(20), [204512]. https://doi.org/10.1063/1.2116987

**Effective density terms in proper integral equations.** / Dyer, Kippi M.; Perkyns, John S.; Pettitt, Bernard.

Research output: Contribution to journal › Article

*Journal of Chemical Physics*, vol. 123, no. 20, 204512. https://doi.org/10.1063/1.2116987

}

TY - JOUR

T1 - Effective density terms in proper integral equations

AU - Dyer, Kippi M.

AU - Perkyns, John S.

AU - Pettitt, Bernard

PY - 2005

Y1 - 2005

N2 - Two complementary routes to a new integral equation theory for site-site molecular fluids are presented. First, a simple approximation to a subset of the atomic site bridge functions in the diagrammatically proper integral equation theory is presented. This in turn leads to a form analogous to the reactive fluid theory, in which the normalization of the intramolecular distribution function and the value of the off-diagonal elements in the density matrix of the proper integral equations are the means of propagating the bridge function approximation. Second, a derivation from a topological expansion of a model for the single-site activity followed by a topological reduction and low-order truncation is given. This leads to an approximate numerical value for the new density coefficient. The resulting equations give a substantial improvement over the standard construction as shown with a series of simple diatomic model calculations.

AB - Two complementary routes to a new integral equation theory for site-site molecular fluids are presented. First, a simple approximation to a subset of the atomic site bridge functions in the diagrammatically proper integral equation theory is presented. This in turn leads to a form analogous to the reactive fluid theory, in which the normalization of the intramolecular distribution function and the value of the off-diagonal elements in the density matrix of the proper integral equations are the means of propagating the bridge function approximation. Second, a derivation from a topological expansion of a model for the single-site activity followed by a topological reduction and low-order truncation is given. This leads to an approximate numerical value for the new density coefficient. The resulting equations give a substantial improvement over the standard construction as shown with a series of simple diatomic model calculations.

UR - http://www.scopus.com/inward/record.url?scp=34047182632&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=34047182632&partnerID=8YFLogxK

U2 - 10.1063/1.2116987

DO - 10.1063/1.2116987

M3 - Article

VL - 123

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 20

M1 - 204512

ER -