### Abstract

Using Löwdin's pairing theorem one can obtain an explicit expression for the overlap repulsion of two "unperturbed" closed-shell molecules at the single determinant level. After some regrouping, the interaction energy can be presented as a sum of terms of different physical meaning, each of which is expressed explicitly in terms of the (paired) molecular orbitals of the interacting molecules. The interaction energy can be decomposed into the following terms: the "naive" electrostatic interaction corresponding to undisturbed charge distributions of the two molecules; the Hartree-Fock exchange calculated neglecting the orbital overlap; "finite basis" terms originating from the deviation of the individual molecular orbitals (MOs) from the Hartree-Fock limit; overlap effects modifying the intramolecular energies as well as the electrostatic and exchange interactions; "true" overlap effects containing intermolecular overlap integrals and intermolecular charge distributions in the one- or two-electron integrals.

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

Pages (from-to) | 53-59 |

Number of pages | 7 |

Journal | International Journal of Quantum Chemistry |

Volume | 82 |

Issue number | 2 |

DOIs | |

Publication status | Published - Mar 15 2001 |

### Fingerprint

### Keywords

- Energy decomposition
- Energy decomposition for intermolecular interactions
- Hydrogen bonding
- Intermolecular interactions
- Löwdin's pairing theorem
- Overlap repulsion
- Pairing theorem

### ASJC Scopus subject areas

- Physical and Theoretical Chemistry

### Cite this

**Overlap repulsion with Löwdin's pairing theorem.** / Hamza, A.; Mayer, I.

Research output: Contribution to journal › Article

}

TY - JOUR

T1 - Overlap repulsion with Löwdin's pairing theorem

AU - Hamza, A.

AU - Mayer, I.

PY - 2001/3/15

Y1 - 2001/3/15

N2 - Using Löwdin's pairing theorem one can obtain an explicit expression for the overlap repulsion of two "unperturbed" closed-shell molecules at the single determinant level. After some regrouping, the interaction energy can be presented as a sum of terms of different physical meaning, each of which is expressed explicitly in terms of the (paired) molecular orbitals of the interacting molecules. The interaction energy can be decomposed into the following terms: the "naive" electrostatic interaction corresponding to undisturbed charge distributions of the two molecules; the Hartree-Fock exchange calculated neglecting the orbital overlap; "finite basis" terms originating from the deviation of the individual molecular orbitals (MOs) from the Hartree-Fock limit; overlap effects modifying the intramolecular energies as well as the electrostatic and exchange interactions; "true" overlap effects containing intermolecular overlap integrals and intermolecular charge distributions in the one- or two-electron integrals.

AB - Using Löwdin's pairing theorem one can obtain an explicit expression for the overlap repulsion of two "unperturbed" closed-shell molecules at the single determinant level. After some regrouping, the interaction energy can be presented as a sum of terms of different physical meaning, each of which is expressed explicitly in terms of the (paired) molecular orbitals of the interacting molecules. The interaction energy can be decomposed into the following terms: the "naive" electrostatic interaction corresponding to undisturbed charge distributions of the two molecules; the Hartree-Fock exchange calculated neglecting the orbital overlap; "finite basis" terms originating from the deviation of the individual molecular orbitals (MOs) from the Hartree-Fock limit; overlap effects modifying the intramolecular energies as well as the electrostatic and exchange interactions; "true" overlap effects containing intermolecular overlap integrals and intermolecular charge distributions in the one- or two-electron integrals.

KW - Energy decomposition

KW - Energy decomposition for intermolecular interactions

KW - Hydrogen bonding

KW - Intermolecular interactions

KW - Löwdin's pairing theorem

KW - Overlap repulsion

KW - Pairing theorem

UR - http://www.scopus.com/inward/record.url?scp=0035868369&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0035868369&partnerID=8YFLogxK

U2 - 10.1002/1097-461X(2001)82:2<53::AID-QUA1029>3.0.CO;2-B

DO - 10.1002/1097-461X(2001)82:2<53::AID-QUA1029>3.0.CO;2-B

M3 - Article

VL - 82

SP - 53

EP - 59

JO - International Journal of Quantum Chemistry

JF - International Journal of Quantum Chemistry

SN - 0020-7608

IS - 2

ER -