Enthalpy difference between conformations of normal alkanes:Intramolecular basis set superposition error (BSSE) in the case of n -butane and n -hexane

• Published in: The Journal of chemical physics 2008-10, Vol.129 (16), p.164101-164101-5
• Main Author: Balabin, Roman M.
• Format: Article
• Language: English
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.2997349

In this paper, an extra error source for high-quality ab initio calculation of conformation equilibrium in normal alkanes-intramolecular basis set superposition error (BSSE)-is discussed. Normal butane ( n -butane) and normal hexane ( n -hexane) are used as representative examples. Single-point energy difference and BSSE values of trans and gauche conformations for n -butane (and trans - trans - trans and gauche - gauche - gauche conformations for n -hexane) were calculated using popular electron correlation methods: The second-order Moller-Plesset (MP2), the fourth-order Moller-Plesset (MP4), and coupled cluster with single and double substitutions with noniterative triple excitation [CCSD(T)] levels of theory. Extrapolation to the complete basis set is applied. The difference between BSSE-corrected and uncorrected relative energy values ranges from ∼ 100   cal / mol (in case of n -butane) to more than 1000 cal/mol (in case of n -hexane). The influence of basis set type (Pople or Dunning) and size [up to 6 - 311 G ( 3 d f , 3 p d ) and aug-cc-pVQZ] is discussed.