Intrinsic errors in several ab initio methods. The dissociation energy of N{sub 2}

Journal Article · Thu Mar 23 04:00:00 EST 1995 · Journal of Physical Chemistry

DOI:https://doi.org/10.1021/j100012a005· OSTI ID:35461

Peterson, K A ^[1]; Dunning, Jr, T H ^[2]

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1. Washington State Univ., Richland, WA (United States)
2. Pacific Northwest Lab., Richland, WA (United States)

Using sequences of correlation consistent basis sets, complete basis set (CBS) limits for the dissociation energy D{sub c} of N{sub 2} have been estimated for a variety of commonly used electron correlation methods. After extrapolation to the CBS limit, the difference between theory and experiment corresponds to the error intrinsic to the chosen theoretical method. Correlated wave functions (valence electrons correlated only) for which intrinsic errors have been estimated include internally contracted multireference configuration interaction (CMRCI), singles and doubles coupled cluster theory with and without perturbative triple excitations [CCSD, CCSD(T)], and second-, third-, and fourth-order Moller-Plesset perturbation theory (MP2, MP3, MP4). For CMRCI and CCSD(T), D{sub c} converges smoothly from below the experimental value and yields the smallest intrinsic errors, -0.8 and -1.6 kcal/mol, respectively. In contrast, for MP2 and MP4, D{sub c} exhibits fortuitously good agreement with experiment for small basis sets but leads to CBS limits that are 11.6 and 3.4 kcal/mol larger than experiment, respectively. Correlation of the 1s core electrons is predicted to yield intrinsic errors of less than 1 kcal/mol for CMRCI and CCSD(T), while those for MP2 and MP4 increase still further. 38 refs., 1 fig., 1 tab.

• Sponsoring Organization: USDOE
• DOE Contract Number: AC06-76RL01830; FG06-89ER75522
• OSTI ID: 35461
• Journal Information: Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 12 Vol. 99; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
66 PHYSICS
99 GENERAL AND MISCELLANEOUS
CONFIGURATION INTERACTION
DISSOCIATION ENERGY
ELECTRONIC STRUCTURE
ERRORS
HARTREE-FOCK METHOD
NITROGEN
NUCLEAR MODELS
PERTURBATION THEORY