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2
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84918222937
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The claim that current ab initio methods operate “from first principles” is in fact somewhat dubious. The basis sets used in them contain numerous parameters whose values can be determined only by optimizing the results of calculations for specific systems. Variational optimization of the results for atoms might perhaps be passed as a marginally “first principles” approach. However, the parameters that are best for atoms are not the best for molecules, and it seems clear that most of the basis sets in current use were in fact chosen to optimize the results for some arbitrary set of molecules.
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3
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0022076689
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Comparisons of this kind are hardly ever given in papers reporting ab initio calculations., For some indication of the magnitude of such errors, see
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(1985)
J. Am. Chem. Soc.
, vol.107
, pp. 3898-3902
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Dewar1
Ford2
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4
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0004573823
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* results for some simple molecules; see, No other comparable tests of any ab initio procedures have as yet been reported.
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(1987)
Chem. Phys. Lett.
, pp. 141-145
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Dewar1
O'Connor2
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5
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0038432047
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For a general account and references, see, American Chemical Society, Washington, DC
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(1992)
A Semiempirical Life
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Dewar1
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10
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84918222936
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EQC includes the use of quantum chemical calculations to make predictions in areas where the method in question has been properly tested.
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11
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0343508672
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For comments on an earlier misuse of the term by Lipscomb et al. and references, see
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(1979)
J. Am. Chem. Soc.
, vol.101
, pp. 5558
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Dewar1
Ford2
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12
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84918222935
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Chemistry provides an exceptionally taxing test of theoretical procedures because the systems studied are often large and complex and because their energies need to be known with exceptional precision, an error of 1 kcal/mol being chemically significant. Even in the case of benzene, this already corresponds to an error of only ±0.001% in the total energy, and the percentage accuracy required becomes progressively smaller for larger systems.
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42
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84986766143
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The thermochemical kinetics of retro- ?ene? reactions of molecules with the general structure (allyl) XYH in the gas phase. IX. The thermal unimolecular decomposition of ethyallylether in the gas phase
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Cited by
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(1974)
International Journal of Chemical Kinetics
, vol.6
, pp. 429
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Walsh1
Egger2
Vitas3
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43
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84918222934
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Calculated from the Eyring equation, assuming a transmission coefficient of unity, using kinetic data reported by Smith, G.G.; Yates, B.L. J. Chem. Soc. 1965, 7242.
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48
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84918222933
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2) and, bφ [[Truncated]]
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51
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84918222931
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Address: Department of Chemistry, University of Missouri, Kansas City, MO 64110, USA.
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52
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84918222930
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Address: Semichem Inc., 12715 West 66th Terrace, Shawnee, KS 66216, USA.
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