### Abstract

We present a computer program, MORATE (Molecular Orbital RATE calculations), for direct dynamics calculations of unimolecular and bimolecular rate constants of gas-phase chemical reactions involving atoms, diatoms, or polyatomic species. The potential energies, gradients, and higher derivatives of the potential are calculated whenever needed by semiempirical molecular orbital theory without the intermediary of a global or semiglobal fit. The dynamical methods used are conventional or variational transition state theory and multidimensional semiclassical approximations for tunneling and nonclassical reflection. The computer program is conveniently interfaced package consisting of the POLYRATE program, version 4.5.1, for dynamical rate calculations, and the MOPAC program, version 5.03, for semiempirical electronic structure computations. All semiempirical methods available in MOPAC, in particular MINDO/3, MNDO, AM1, and PM3, can be called on to calculate the potential and gradient. Higher derivatives of the potential are obtained by numerical derivatives of the gradient. Variational transition states are found by a one-dimensional search of generalized-transition-state dividing surfaces perpendicular to the minimum-energy path, and tunneling probabilities are evaluated by numerical quadrature.

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

Pages (from-to) | 143-159 |

Number of pages | 17 |

Journal | Computer Physics Communications |

Volume | 75 |

Issue number | 1-2 |

DOIs | |

State | Published - 1993 |

Externally published | Yes |

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### ASJC Scopus subject areas

- Computer Science Applications
- Physics and Astronomy(all)

### Cite this

*Computer Physics Communications*,

*75*(1-2), 143-159. https://doi.org/10.1016/0010-4655(93)90172-9

**MORATE : a program for direct dynamics calculations of chemical reaction rates by semiempirical molecular orbital theory.** / Truong, Thanh N.; Lu, Da hong; Lynch, Gillian C.; Liu, Yi Ping; Melissas, Vasilios S.; Stewart, James J P; Steckler, Rozeanne; Garrett, Bruce C.; Isaacson, Alan D.; Gonzalez-Lafont, Angels; Rai, Sachchida N.; Hancock, Gene C.; Joseph, Tomi; Truhlar, Donald G.

Research output: Contribution to journal › Article

*Computer Physics Communications*, vol. 75, no. 1-2, pp. 143-159. https://doi.org/10.1016/0010-4655(93)90172-9

}

TY - JOUR

T1 - MORATE

T2 - a program for direct dynamics calculations of chemical reaction rates by semiempirical molecular orbital theory

AU - Truong, Thanh N.

AU - Lu, Da hong

AU - Lynch, Gillian C.

AU - Liu, Yi Ping

AU - Melissas, Vasilios S.

AU - Stewart, James J P

AU - Steckler, Rozeanne

AU - Garrett, Bruce C.

AU - Isaacson, Alan D.

AU - Gonzalez-Lafont, Angels

AU - Rai, Sachchida N.

AU - Hancock, Gene C.

AU - Joseph, Tomi

AU - Truhlar, Donald G.

PY - 1993

Y1 - 1993

N2 - We present a computer program, MORATE (Molecular Orbital RATE calculations), for direct dynamics calculations of unimolecular and bimolecular rate constants of gas-phase chemical reactions involving atoms, diatoms, or polyatomic species. The potential energies, gradients, and higher derivatives of the potential are calculated whenever needed by semiempirical molecular orbital theory without the intermediary of a global or semiglobal fit. The dynamical methods used are conventional or variational transition state theory and multidimensional semiclassical approximations for tunneling and nonclassical reflection. The computer program is conveniently interfaced package consisting of the POLYRATE program, version 4.5.1, for dynamical rate calculations, and the MOPAC program, version 5.03, for semiempirical electronic structure computations. All semiempirical methods available in MOPAC, in particular MINDO/3, MNDO, AM1, and PM3, can be called on to calculate the potential and gradient. Higher derivatives of the potential are obtained by numerical derivatives of the gradient. Variational transition states are found by a one-dimensional search of generalized-transition-state dividing surfaces perpendicular to the minimum-energy path, and tunneling probabilities are evaluated by numerical quadrature.

AB - We present a computer program, MORATE (Molecular Orbital RATE calculations), for direct dynamics calculations of unimolecular and bimolecular rate constants of gas-phase chemical reactions involving atoms, diatoms, or polyatomic species. The potential energies, gradients, and higher derivatives of the potential are calculated whenever needed by semiempirical molecular orbital theory without the intermediary of a global or semiglobal fit. The dynamical methods used are conventional or variational transition state theory and multidimensional semiclassical approximations for tunneling and nonclassical reflection. The computer program is conveniently interfaced package consisting of the POLYRATE program, version 4.5.1, for dynamical rate calculations, and the MOPAC program, version 5.03, for semiempirical electronic structure computations. All semiempirical methods available in MOPAC, in particular MINDO/3, MNDO, AM1, and PM3, can be called on to calculate the potential and gradient. Higher derivatives of the potential are obtained by numerical derivatives of the gradient. Variational transition states are found by a one-dimensional search of generalized-transition-state dividing surfaces perpendicular to the minimum-energy path, and tunneling probabilities are evaluated by numerical quadrature.

UR - http://www.scopus.com/inward/record.url?scp=0027577788&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0027577788&partnerID=8YFLogxK

U2 - 10.1016/0010-4655(93)90172-9

DO - 10.1016/0010-4655(93)90172-9

M3 - Article

VL - 75

SP - 143

EP - 159

JO - Computer Physics Communications

JF - Computer Physics Communications

SN - 0010-4655

IS - 1-2

ER -