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5
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84952290161
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(e) First‐ and second‐row transition metals: W. J. Pietro and W. J. Hehre, Organometallics (submitted).
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12
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16444380210
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Such an approach has been utilized by Carlsen who obtained equilibrium geometries for a number of polyatomic molecules in excellent agreement with those derived from near‐limiting Hartree‐Fock procedures simply by using the 4-31G split‐valence basis set (Ref. 5) supplemented by a single set of Gaussian s ‐ and p ‐type functions placed along chemical bonds.
-
(1977)
Chem. Phys. Lett
, vol.51
, pp. 192
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Carlsen, N.R.1
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26
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84952290159
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Quantum Chemistry Program Exchange, Indiana University, Bloomington, Indiana.
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Binkley, J.S.1
Whiteside, R.A.2
Krishnan, R.3
Schlegel, H.B.4
Seeger, R.5
DeFrees, D.J.6
Pople, J.A.7
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27
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85034697310
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Jr., B. A. Levi, and W. J. Hehre, J. Am. Chem. Soc. (to be published).
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Hout, R.F.1
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29
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85034697382
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Heats of formation were corrected to 0 K using [formula omitted] where the corrections [formula omitted] can be calculated from statistical mechanics. In practice, when correcting heats of reaction, it is not necessary to calculate the corrections for the elements which are involved as the contributions from each side of the reaction will cancel. Assuming a rigid‐rotor/harmonic oscillator model, at temperatures high enough that the rotation may be treated classically, [formula omitted] is given as [formula omitted] for a nonlinear molecule, and as [formula omitted] for a linear molecule. These equations are valid for nearly all cases. The major exception is [formula omitted] for which a nonclassical treatment of the rotation is required even at fairly high temperatures; the resulting value of the correction [formula omitted] is [formula omitted] Where available, experimental frequencies were used; in cases where they were not, frequencies were obtained theoretically from 3‐21G level calculations. On the average such frequencies are larger than their corresponding experimental values by 11%. Therefore all calculated frequencies were scaled by 0. 89 before use. The heats of formation were also corrected for the zero point energy of vibration [formula omitted] where N is the number of normal modes, [formula omitted] for nonlinear molecules, [formula omitted] for linear molecules. Normal modes which correspond to torsions or Inversions and with frequencies less than [formula omitted] were treated as rotations. For each such mode the vibrational component of the enthalpy correction is replaced by a rotational term [formula omitted]
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