IS TETRAHEDRAL H-4(2+) A MINIMUM - ANOMALOUS BEHAVIOR OF POPULAR BASIS-SETS WITH THE STANDARD P-EXPONENTS ON HYDROGEN
Glukhovtsev M, Schleyer P, van Eikema Hommes N, Walkimar de M. Carneiro J, Koch W (1993)
Publication Status: Published
Publication Type: Journal article
Publication year: 1993
Journal
Publisher: Wiley-Blackwell
Book Volume: 14
Pages Range: 285-294
Journal Issue: 3
Abstract
The nature of the tetrahedral H-4(2+) stationary point (minimum or triply degenerate saddle) depends remarkably upon the theoretical level employed. Harmonic vibrational analyses with, e.g., the 6-31G** (and 6-31 + + G**) and Dunning's [4s2p1d;2s1p] [D95(d,p)] basis sets using the standard p exponent suggest (erroneously!) that the T(d) geometry is a minimum at both the HF and MP2 levels. This is not the case at definitive higher levels. The C3H42+ structure with an apical H is another example of the failure of the calculations with the 6-31G**, 6-311G**, and D95(d,p) basis sets. Even at MP2/6-31G** and MP2/cc-pVDZ levels, the C3v structure has no negative eigenvalues of the Hessian. Actually, this form is a second-order saddle point as shown by the MP2/6-31G** calculation with the optimized exponent. The D4h methane dication structure is also an example of the misleading performance of the 6-31G** basis set. In all these cases, energy-optimized hydrogen p exponents give the correct results, i.e., those found with more extended treatments. Optimized values of the hydrogen polarization function exponents eliminate these defects in 6-31G** calculations. Species with higher coordinate hydrogens may also be calculated reliably by using more than one set of p functions on hydrogen [e.g., the 6-31G(d,2p) basis set]. Not all cases are critical. A survey of examples, also including some boron compounds, provides calibration.
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APA:
Glukhovtsev, M., Schleyer, P., van Eikema Hommes, N., Walkimar de M. Carneiro, J., & Koch, W. (1993). IS TETRAHEDRAL H-4(2+) A MINIMUM - ANOMALOUS BEHAVIOR OF POPULAR BASIS-SETS WITH THE STANDARD P-EXPONENTS ON HYDROGEN. Journal of Computational Chemistry, 14(3), 285-294. https://dx.doi.org/10.1002/jcc.540140305
MLA:
Glukhovtsev, Mikhail, et al. "IS TETRAHEDRAL H-4(2+) A MINIMUM - ANOMALOUS BEHAVIOR OF POPULAR BASIS-SETS WITH THE STANDARD P-EXPONENTS ON HYDROGEN." Journal of Computational Chemistry 14.3 (1993): 285-294.
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