Benchmark calculations with correlated molecular wavefunctions.  XIII. Potential energy curves for He2, Ne2, and Ar2 using correlation consistent basis sets through augmented sextuple zeta

Tanja Van Mourik, Angela K. Wilson, Thom H. Dunning, Jr.

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328 Citations (Scopus)

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 languageEnglish
Pages (from-to)529-547
Number of pages19
JournalMolecular Physics
Volume96
Publication statusPublished - 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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