### Abstract

Accurate quantum-mechanical calculations of rate constants for a model of reaction in solution are used as benchmarks for two approximate methods: variational transition-state theory with semiclassical corrections for reaction coordinate motion, and the path-integral centroid density method. The reaction model corresponds to a single solute coordinate coupled to a harmonic bath mode. When the harmonic frequency of the bath oscillator is sufficiently high, the results of the approximate methods agree well with the accurate quantum-mechanical ones. For the lowest-frequency bath oscillator considered, the agreement is not as good, but still satisfactory; the worst discrepancies are a factor of 2.0 for the centroid density methods and a factor of 3.3 for variational transition-state theory with semiclassical tunneling corrections. Applications of the approximate methods to models including up to ten bath oscillators indicate that a single bath oscillator provides a reasonable model of a converged harmonic bath.

Original language | English |
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Pages (from-to) | 7392-7404 |

Number of pages | 13 |

Journal | Journal of Chemical Physics |

Volume | 97 |

Issue number | 10 |

Publication status | Published - 1992 |

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### ASJC Scopus subject areas

- Atomic and Molecular Physics, and Optics

### Cite this

*Journal of Chemical Physics*,

*97*(10), 7392-7404.

**Critical comparison of approximate and accurate quantum-mechanical calculations of rate constants for a model activated reaction in solution.** / McRae, Robin P.; Schenter, Gregory K.; Garrett, Bruce C.; Haynes, George R.; Voth, Gregory A.; Schatz, George C.

Research output: Contribution to journal › Article

*Journal of Chemical Physics*, vol. 97, no. 10, pp. 7392-7404.

}

TY - JOUR

T1 - Critical comparison of approximate and accurate quantum-mechanical calculations of rate constants for a model activated reaction in solution

AU - McRae, Robin P.

AU - Schenter, Gregory K.

AU - Garrett, Bruce C.

AU - Haynes, George R.

AU - Voth, Gregory A.

AU - Schatz, George C

PY - 1992

Y1 - 1992

N2 - Accurate quantum-mechanical calculations of rate constants for a model of reaction in solution are used as benchmarks for two approximate methods: variational transition-state theory with semiclassical corrections for reaction coordinate motion, and the path-integral centroid density method. The reaction model corresponds to a single solute coordinate coupled to a harmonic bath mode. When the harmonic frequency of the bath oscillator is sufficiently high, the results of the approximate methods agree well with the accurate quantum-mechanical ones. For the lowest-frequency bath oscillator considered, the agreement is not as good, but still satisfactory; the worst discrepancies are a factor of 2.0 for the centroid density methods and a factor of 3.3 for variational transition-state theory with semiclassical tunneling corrections. Applications of the approximate methods to models including up to ten bath oscillators indicate that a single bath oscillator provides a reasonable model of a converged harmonic bath.

AB - Accurate quantum-mechanical calculations of rate constants for a model of reaction in solution are used as benchmarks for two approximate methods: variational transition-state theory with semiclassical corrections for reaction coordinate motion, and the path-integral centroid density method. The reaction model corresponds to a single solute coordinate coupled to a harmonic bath mode. When the harmonic frequency of the bath oscillator is sufficiently high, the results of the approximate methods agree well with the accurate quantum-mechanical ones. For the lowest-frequency bath oscillator considered, the agreement is not as good, but still satisfactory; the worst discrepancies are a factor of 2.0 for the centroid density methods and a factor of 3.3 for variational transition-state theory with semiclassical tunneling corrections. Applications of the approximate methods to models including up to ten bath oscillators indicate that a single bath oscillator provides a reasonable model of a converged harmonic bath.

UR - http://www.scopus.com/inward/record.url?scp=0001544866&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0001544866&partnerID=8YFLogxK

M3 - Article

VL - 97

SP - 7392

EP - 7404

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 10

ER -