A scheme of atom equivalents for relating ab initio energies to heats of formation

Yala, Zhang

doi:10.1016/0166-1280(90)85025-i

Cited by 18 publications

(11 citation statements)

References 5 publications

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“…(81, the summation is over the n correction terms, each of which is applied k i j times and only on the right side of the formation reaction for molecule i. A; is the error in its calculated A; = AH;, ,(talc) -AH;, ,(exp) (9) gaseous heat of formation, and m is the number of molecules in the database, 54. The minimization of Z was carried out by means of a multidimensional pattern search in which all xi are varied simultaneously through small steps, the lengths of which are adjusted individually to provide the steepest descent of Z.28,z9…”

Section: Procedures and Resultsmentioning

confidence: 99%

Nonlocal density functional calculation of gas phase heats of formation

Habibollahzadeh¹,

Grice²,

Concha³

et al. 1995

J Comput Chem

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A general procedure is presented for computing the gas phase heats of formation of a wide variety of organic compounds. A E for the formation of the molecule from its elements at 0 K is obtained from density functional calculations (Gaussian 92/DFT) for optimized geometries. This result is converted to AH at 298 K by assuming ideal behavior and adding the translational, rotational, and vibrational energies. Additive correction terms corresponding to the various coordination states of the carbons, nitrogens, and oxygens were developed using a database of 54 compounds. The experimental AH; values of these compounds are then reproduced with an average absolute error of 3 kcal/mol and a standard deviation of 4 kcal/mol. For a group of 10 test cases that were not part of the database, the average absolute error is 3.5 kcal/mol and the standard deviation is 4.1 kcal/mol. 0 1995 by John Wiley & Sons, Inc.

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Section: Procedures and Resultsmentioning

confidence: 99%

Nonlocal density functional calculation of gas phase heats of formation

Habibollahzadeh¹,

Grice²,

Concha³

et al. 1995

J Comput Chem

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“…In order to obtain an estimate of that part of E total which can be attributed to a 'solid-like' X atom of the cluster, surrounded only by X atoms, we employed the energy partitioning method of Refs. 7,[14][15][16] : E total is approximated by a sum of energy contributions of the bare X atom, XH and XH 2 groups…”

Section: Hartree-fock Calculationsmentioning

confidence: 99%

Electron correlations for ground-state properties of group-IV semiconductors

1995

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“…The average error in calculated Δ H f °(g)'s for benzenoid aromatics (with and without aliphatic and olefinic substituents) is of the order of 2.5 kcal/mol with several much larger errors for individual outliers. In extending these procedures, several studies of group additivity methods limited to catacondensed and pericondensed unsubstituted benzenoid polycyclic aromatic hydrocarbons (PAHs) have demonstrated that empirical or theoretical estimates of the resonance energy of each compound must be included to yield higher-quality regressions of Δ H f °(g) data. − There also exist many examples of the modeling of Δ H f °(g) values for various classes of organic compounds using calculated ab initio or semiempirical energies combined with element type or atom-hybridization incremental additivity parameters. ,− The rationale and practical justifications for such procedures have previously been discussed. , …”

Section: Introductionmentioning

confidence: 99%

Molecular Structure Parameters and Predictions of Enthalpies of Formation for Catacondensed and Pericondensed Polycyclic Aromatic Hydrocarbons

Biedermann

Agranat

1998

J. Org. Chem.

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Simple procedures that combine calculated ab initio theoretical energies with empirical structural parameters to correlate experimental enthalpies of formation for polycyclic aromatic hydrocarbons are evaluated for predictive potential. The analyzed data set consists of every benzenoid PAH with an experimentally determined DeltaH(f) degrees (g), i.e., nine catacondensed and three pericondensed aromatic compounds. The tested levels of theory use optimized STO-3G, 3-21G, and 6-31G calculated HF electronic energies, and energies determined at the correlated, optimized DFT B3LYP/6-31G and single point MP2/6-31G//HF/6-31G levels. The highest precision correlations of the DeltaH(f) degrees (g) data combine computed electronic energies with three types of parametrized carbon structure descriptors and a CH parameter. The predictive accuracy of this protocol is assessed using a statistical cross-validation procedure.

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A scheme of atom equivalents for relating ab initio energies to heats of formation

Cited by 18 publications

References 5 publications

Nonlocal density functional calculation of gas phase heats of formation

Nonlocal density functional calculation of gas phase heats of formation

Electron correlations for ground-state properties of group-IV semiconductors

Molecular Structure Parameters and Predictions of Enthalpies of Formation for Catacondensed and Pericondensed Polycyclic Aromatic Hydrocarbons

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