Journalartikel

Jahr der Veröffentlichung: 2016

Seiten: 49-58

Zeitschrift: Journal of Computational Physics

Bandnummer: 37

Heftnummer: 1

ISSN: 0192-8651

Open Access Status: Green

DOI Link: https://doi.org/10.1002/jcc.23963

Verlag: Elsevier

Abstract: 

Hydrocarbon cages are key reference materials for the validation and
parameterization of computationally cost‐effective procedures such as
density functional theory (DFT), semiempirical molecular orbital theory,
and molecular mechanics. We obtain accurate total atomization energies
(TAEs) and heats of formation (Δ_fH°₂₉₈) for platonic and prismatic hydrocarbon cages by means of the Wn‐F12 explicitly correlated thermochemical protocols. We consider the following kinetically stable (CH)_n
polycyclic hydrocarbon cages: (i) platonic hydrocarbons (tetrahedrane,
cubane, and dodecahedrane), (ii) prismatic hydrocarbons (triprismane,
cubane, and pentaprismane), and (iii) one truncated tetrahedrane
(octahedrane). Our best theoretical heat of formation for cubane (144.8
kcal mol⁻¹) suggests that the experimental value adopted by the NIST thermochemical database (142.7 ± 1.2 kcal mol⁻¹) should be revised upwards by ∼2 kcal mol⁻¹. Our best heat of formation for dodecahedrane (20.2 kcal mol⁻¹) suggests that the semiexperimental value (22.4 ± 1 kcal mol⁻¹) should be revised downward by ∼2 kcal mol⁻¹. We use our benchmark Wn‐F12
TAEs to evaluate the performance of a variety of computationally less
demanding composite thermochemical procedures. These include the
Gaussian‐n (Gn) and the complete basis set (CBS) methods.
The CBS‐QB3 and CBS‐APNO procedures show relatively poor performance
with root‐mean‐squared deviations (RMSDs) of 4.2 and 2.5 kcal mol⁻¹, respectively. The best performers of the Gn procedures are G4 and G3(MP2)B3 (RMSD = 0.5 and 0.6 kcal mol⁻¹, respectively), while the worst performers are G3 and G4(MP2)‐6X (RMSD = 2.1 and 2.9 kcal mol⁻¹,
respectively). Isodesmic and even homodesmotic reactions involving
these species are surprisingly challenging targets for DFT computations.

Harvard-Zitierstil: Karton, A., Schreiner, P. and Martin, J. (2016) Heats of formation of platonic hydrocarbon cages by means of high‐level thermochemical procedures, Journal of Computational Physics, 37(1), pp. 49-58. https://doi.org/10.1002/jcc.23963

APA-Zitierstil: Karton, A., Schreiner, P., & Martin, J. (2016). Heats of formation of platonic hydrocarbon cages by means of high‐level thermochemical procedures. Journal of Computational Physics. 37(1), 49-58. https://doi.org/10.1002/jcc.23963