### Abstract

Interference-corrected explicitly correlated second-order perturbation theory (INT-MP2-F12) is applied to accelerate the convergence to the completebasis- set limit of coupled-cluster computations. Adding energy terms obtained from INT-MP2-F12 theory to the energies obtained from coupled-cluster singles-and-doubles (CCSD) computations yields a mean absolute deviation (MAD) from explicitly correlated CCSD results below 1 kJ/mol for a test set of 106 molecules. A composite scheme for the computation of atomization energies is assessed. This scheme is denoted as CCSD(T)+F12+INT and consists of the CCSD model with perturbative triples (CCSD(T)) supplemented with INT-MP2-F12 corrections, using a quadruple-zeta quality basis set (cc-pVQZ-F12). The composite scheme achieves chemical accuracy with respect to experimentally derived or computed reference values. Using Boys localized molecular orbitals, the MAD of the CCSD(T)+F12+INT/cc-pVQZ-F12 atomization energies from the reference values is below 1 kJ/mol for the G2/97 test set.

Original language | English (US) |
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Pages (from-to) | 1-12 |

Number of pages | 12 |

Journal | Theoretical Chemistry Accounts |

Volume | 133 |

Issue number | 3 |

DOIs | |

State | Published - Jan 30 2014 |

### Keywords

- Atomization energy
- Coupled-cluster theory
- Explicit correlation
- Interference effects
- Performance assessment
- Test set

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## Cite this

*Theoretical Chemistry Accounts*,

*133*(3), 1-12. https://doi.org/10.1007/s00214-014-1446-0