ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Ab initio calculations on conformations corresponding to the torsional energy minima and maxima of ethane, methylamine, methanol, hydrazine, hydroxylamine, and hydrogen peroxide were carried out with geometry optimizations using second-order Møller–Plesset perturbation theory (MP2) in the 6–311+G(3df,2p) basis. Compared with experiments the MP2/6–311+G(3df,2p) calculations yield absolute average deviations of 0.128 kcal/mol for 6 rotational barriers, 0.009 A(ring) for 18 bond lengths, 0.7° for 16 bond angles, 0.5° for 2 dihedral angles, and 0.17 D for 5 dipole moments. Three smaller basis sets, 6–31G(d), 6–31+G(d,p), and 6–311G(d,p), were also used to study variations in the total energies and barrier heights as a result of basis set expansions. Several single-point calculations were performed to estimate effects of electron correlation enhancement from MP2 to quadratic configuration interaction [QCISD(T)]. Simulating a high level calculation with lower level calculations in a procedure similar to the recent G2(MP2) theory was found very successful. © 1995 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.469101
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