### Abstract

The utility of the separated electron pair (SEP) model (strongly orthogonal geminals) is examined quantitatively, for pyramidal and planar nuclear configurations of the NH_{3} molecule. The best SEP wave function computed for each species is capable of recovering about half of the correlation energy obtained by a fairly accurate configuration interaction (CI) calculation, (corresponding to roughly 25% of the total molecular correlation energy). It is illustrated that the model can be systematically extended with only a modest effort to yield more accurate results (about 40% of the total correlation energy). The fact that the corrections to the SEP model have a simple physical interpretation suggests that this model may be a useful starting point for “brute force” CI calculations on larger chemical systems.

Original language | English |
---|---|

Pages (from-to) | 365-387 |

Number of pages | 23 |

Journal | International Journal of Quantum Chemistry |

Volume | 4 |

Issue number | 4 |

DOIs | |

Publication status | Published - 1970 |

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### ASJC Scopus subject areas

- Atomic and Molecular Physics, and Optics
- Condensed Matter Physics
- Physical and Theoretical Chemistry

### Cite this

**The generalized separated electron pair model. 1. An application to NH _{3} .** / Robb, M. A.; Csizmadia, I.

Research output: Contribution to journal › Article

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*International Journal of Quantum Chemistry*, vol. 4, no. 4, pp. 365-387. https://doi.org/10.1002/qua.560040404

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TY - JOUR

T1 - The generalized separated electron pair model. 1. An application to NH3

AU - Robb, M. A.

AU - Csizmadia, I.

PY - 1970

Y1 - 1970

N2 - The utility of the separated electron pair (SEP) model (strongly orthogonal geminals) is examined quantitatively, for pyramidal and planar nuclear configurations of the NH3 molecule. The best SEP wave function computed for each species is capable of recovering about half of the correlation energy obtained by a fairly accurate configuration interaction (CI) calculation, (corresponding to roughly 25% of the total molecular correlation energy). It is illustrated that the model can be systematically extended with only a modest effort to yield more accurate results (about 40% of the total correlation energy). The fact that the corrections to the SEP model have a simple physical interpretation suggests that this model may be a useful starting point for “brute force” CI calculations on larger chemical systems.

AB - The utility of the separated electron pair (SEP) model (strongly orthogonal geminals) is examined quantitatively, for pyramidal and planar nuclear configurations of the NH3 molecule. The best SEP wave function computed for each species is capable of recovering about half of the correlation energy obtained by a fairly accurate configuration interaction (CI) calculation, (corresponding to roughly 25% of the total molecular correlation energy). It is illustrated that the model can be systematically extended with only a modest effort to yield more accurate results (about 40% of the total correlation energy). The fact that the corrections to the SEP model have a simple physical interpretation suggests that this model may be a useful starting point for “brute force” CI calculations on larger chemical systems.

UR - http://www.scopus.com/inward/record.url?scp=84987108785&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84987108785&partnerID=8YFLogxK

U2 - 10.1002/qua.560040404

DO - 10.1002/qua.560040404

M3 - Article

VL - 4

SP - 365

EP - 387

JO - International Journal of Quantum Chemistry

JF - International Journal of Quantum Chemistry

SN - 0020-7608

IS - 4

ER -