### Abstract

Complete harmonic force fields have been calculated for the ground state (S_{0}) and the first excited singlet state (S_{1}) of naphthalene using the multiconfiguration self-consistent field (MCSCF) approach. Identical calculations were performed for benzene to test the methodology with already available theoretical and empirical force fields. Two different basis sets were applied (STO-3G and near double-zeta) and all π-orbitals included in the active space. The geometries of ground and excited states were separately optimized. Following the ideas of Pulay, the force constants were scaled before calculating frequencies and normal modes. For the ground states the influence of correlation is discussed by comparison with Pulay's results. Except for special vibrations where correlation effects turn out to be important, the use of Pulay's scaling factors leads to a satisfactory description of the in-plane-vibrations. In the case of benzene the calculated frequency shifts between S_{0} and S_{1} are in complete qualitative agreement with experimental observations. In the case of naphthalene the new theoretical results suggest several revisions of earlier empirical assignments.

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

Pages (from-to) | 974-987 |

Number of pages | 14 |

Journal | Journal of Chemical Physics |

Volume | 98 |

Issue number | 2 |

Publication status | Published - 1993 |

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### ASJC Scopus subject areas

- Atomic and Molecular Physics, and Optics

### Cite this

*Journal of Chemical Physics*,

*98*(2), 974-987.

**Theoretical prediction of the vibrational spectrum of naphthalene in the first excited singlet state.** / Swiderek, Petra; Hohlneicher, Georg; Maluendes, Sergio A.; Dupuis, Michel.

Research output: Contribution to journal › Article

*Journal of Chemical Physics*, vol. 98, no. 2, pp. 974-987.

}

TY - JOUR

T1 - Theoretical prediction of the vibrational spectrum of naphthalene in the first excited singlet state

AU - Swiderek, Petra

AU - Hohlneicher, Georg

AU - Maluendes, Sergio A.

AU - Dupuis, Michel

PY - 1993

Y1 - 1993

N2 - Complete harmonic force fields have been calculated for the ground state (S0) and the first excited singlet state (S1) of naphthalene using the multiconfiguration self-consistent field (MCSCF) approach. Identical calculations were performed for benzene to test the methodology with already available theoretical and empirical force fields. Two different basis sets were applied (STO-3G and near double-zeta) and all π-orbitals included in the active space. The geometries of ground and excited states were separately optimized. Following the ideas of Pulay, the force constants were scaled before calculating frequencies and normal modes. For the ground states the influence of correlation is discussed by comparison with Pulay's results. Except for special vibrations where correlation effects turn out to be important, the use of Pulay's scaling factors leads to a satisfactory description of the in-plane-vibrations. In the case of benzene the calculated frequency shifts between S0 and S1 are in complete qualitative agreement with experimental observations. In the case of naphthalene the new theoretical results suggest several revisions of earlier empirical assignments.

AB - Complete harmonic force fields have been calculated for the ground state (S0) and the first excited singlet state (S1) of naphthalene using the multiconfiguration self-consistent field (MCSCF) approach. Identical calculations were performed for benzene to test the methodology with already available theoretical and empirical force fields. Two different basis sets were applied (STO-3G and near double-zeta) and all π-orbitals included in the active space. The geometries of ground and excited states were separately optimized. Following the ideas of Pulay, the force constants were scaled before calculating frequencies and normal modes. For the ground states the influence of correlation is discussed by comparison with Pulay's results. Except for special vibrations where correlation effects turn out to be important, the use of Pulay's scaling factors leads to a satisfactory description of the in-plane-vibrations. In the case of benzene the calculated frequency shifts between S0 and S1 are in complete qualitative agreement with experimental observations. In the case of naphthalene the new theoretical results suggest several revisions of earlier empirical assignments.

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M3 - Article

VL - 98

SP - 974

EP - 987

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 2

ER -