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Title: High-level theoretical study of the conformational equilibrium of n-pentane
Authors: SALAM, Akbar 
DELEUZE, Michael 
Issue Date: 2002
Source: JOURNAL OF CHEMICAL PHYSICS, 116(4). p. 1296-1302
Abstract: An accurate calculation of the energy differences between stationary points on the torsional potential energy surface of n-pentane is performed using ab initio Hartree-Fock theory, advanced many-body methods such as MP2, MP3, CCSD, and CCSD(T), as well as density functional theory, together with basis sets of increasing size. This study focuses on the four conformers of this compound, namely, the all staggered trans-trans (TT), trans-gauche (TG), gauche-gauche (G(+)G(+)), and gauche-gauche (G(+)G(-)) structures. belonging to the C-2v, C-1, C-2, and C-1 symmetry point groups, respectively. A focal point analysis up to 635 basis functions is carried out to determine when the series of relative energies of the four conformers approach convergence. It is found that relative to the minimum energy TT conformer. the energy differences of the TG, G(+)G(+), and G(+)G(-) conformers obtained from ab initio methods are 0.621, 1.065, and 2.917 kcal mol(-1), respectively. Converged energy differences obtained with three density functionals, B3PW91, B3LYP, and MPW1K, are found to be considerably higher than those computed ab initio. Mole fractions of the various conformers are evaluated at different temperatures from thermostatistical data accounting for vibrational and rotational entropies, as well as zero-point vibrational energies in the rigid rotor-harmonic oscillator approximation. (C) 2002 American Institute of Physics.
Notes: Limburgs Univ Ctr, Dept SBG, B-3590 Diepenbeek, Belgium. Limburgs Univ Ctr, Inst Mat Res, IMO, B-3590 Diepenbeek, Belgium.Salam, A, Texas Tech Univ, Dept Chem & Biochem, POB 41061, Lubbock, TX 79409 USA.
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ISSN: 0021-9606
e-ISSN: 1089-7690
DOI: 10.1063/1.1429243
ISI #: 000173384200010
Category: A1
Type: Journal Contribution
Validations: ecoom 2003
Appears in Collections:Research publications

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