### Abstract

A valence-type anion of the canonical tautomer of uracil has been characterized using explicitly correlated second-order Møller-Plesset perturbation theory (RI-MP2-R12) in conjunction with conventional coupled-cluster theory with single, double, and perturbative triple excitations. At this level of electron-correlation treatment and after inclusion of a zero-point vibrational energy correction, determined in the harmonic approximation at the RI-MP2 level of theory, the valence anion is adiabatically stable with respect to the neutral molecule by 40 meV. The anion is characterized by a vertical detachment energy of 0.60 eV. To obtain accurate estimates of the vertical and adiabatic electron binding energies, a scheme was applied in which electronic energy contributions from various levels of theory were added, each of them extrapolated to the corresponding basis-set limit. The MP2 basis-set limits were also evaluated using an explicitly correlated approach, and the results of these calculations are in agreement with the extrapolated values. A remarkable feature of the valence anionic state is that the adiabatic electron binding energy is positive but smaller than the adiabatic electron binding energy of the dipole-bound state. © 2007 American Institute of Physics.

Original language | English |
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Article number | 085101 |

Journal | Journal of Chemical Physics |

Volume | 126 |

Issue number | 8 |

DOIs | |

Publication status | Published - 2007 |

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## Cite this

*Journal of Chemical Physics*,

*126*(8), [085101]. https://doi.org/10.1063/1.2436890