## Abstract

The potential energy curves of the rare gas dimers He-2, Ne-2, and Ar-2 have been computed using correlation consistent basis sets ranging from singly augmented aug-cc-pVDZ sets through triply augmented t-aug-cc-pV6Z sets, with the augmented sextuple basis sets being reported herein. Several methods for including electron correlation were investigated, namely Moller-Plesset perturbation theory (MP2, MP3 and MP4) and coupled cluster theory [CCSD and CCSD(T)]. For He-2 CCSD(T)/d-aug-cc-pV6Z calculations yield a well depth of 7.35 cm(-1) (10.58 K), with an estimated complete basis set (CBS) limit of 7.40 cm(-1) (10.65 K). The latter is smaller than the 'exact' well depth (Aziz, R. A., Janzen, A. R., and Moldover, M. R., 1995, Phys. Rev. Lett., 74, 1586) by about 0.2 cm(-1) (0.35 K). The Net well depth, computed with the CCSD(T)/d-aug-cc-pV6Z method, is 28.31 cm(-1) and the estimated CBS limit is 28.4 cm(-1) approximately 1 cm(-1) smaller than the empirical potential of Aziz, R. A., and Slaman, M., J., 1989, Chem. Phys., 130, 187. Inclusion of core and core-valence correlation effects has a negligible effect on the Nea well depth, decreasing it by only 0.04 cm(-1). For Ar-2, CCSD(T)/ d-aug-cc-pV6Z calculations yield a well depth of 96.2 cm(-1). The corresponding HFDID potential of Aziz, R. A., 1993, J. chem. Phys., 99, 4518 predicts of D-e of 99.7 cm(-1). Inclusion of core and core-valence effects in Ar-2 increases the well depth and decreases the discrepancy by approximately 1 cm(-1).

Original language | English |
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Pages (from-to) | 529-547 |

Number of pages | 19 |

Journal | Molecular Physics |

Volume | 96 |

Publication status | Published - 20 Feb 1999 |

## Keywords

- GAUSSIAN-BASIS SETS
- CONFIGURATION-INTERACTION CALCULATIONS
- PERTURBATIVE ABINITIO CALCULATIONS
- AB-INITIO CALCULATIONS
- WAVE-FUNCTIONS
- MOLLER-PLESSET
- HELIUM DIMER
- VARIATIONAL CALCULATIONS
- SUPERPOSITION ERROR
- ELECTRON-AFFINITIES

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