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A Comparison of Density Functional Theory with Ab initio Approaches for Systems Involving First Transition Row MetalsDensity functional theory (DFT) is found to give a better description of the geometries and vibrational frequencies of FeL and FeL(sup +) systems than second order Moller Plesset perturbation theory (MP2). Namely, the DFT correctly predicts the shift in the CO vibrational frequency between free CO and the Sigma(sup -) state of FeCO and yields a good result for the Fe-C distance in the quartet states of FeCH4(+) 4 These are properties where the MP2 results are unsatisfactory. Thus DFT appears to be an excellent approach for optimizing the geometries and computing the zero-point energies of systems containing first transition row atoms. Because the DFT approach is biased in favor of the 3d(exp 7) occupation, whereas the more traditional approaches are biased in favor of the 3d(exp 6) occupation, differences are found in the relative ordering of states. It is shown that if the dissociation is computed to the most appropriate atomic asymptote and corrected to the ground state asymptote using the experimental separations, the DFT results are in good agreement with high levels of theory. The energetics at the DFT level are much superior to the MP2 and in most cases in good agreement with high levels of theory.
Document ID
20010110785
Acquisition Source
Ames Research Center
Document Type
Preprint (Draft being sent to journal)
Authors
Ricca, Alessandra
(NASA Ames Research Center Moffett Field, CA United States)
Bauschlicher, Charles W.
(NASA Ames Research Center Moffett Field, CA United States)
Langhoff, Stephen R.
Date Acquired
August 20, 2013
Publication Date
January 1, 1994
Subject Category
Mathematical And Computer Sciences (General)
Funding Number(s)
PROJECT: RTOP 232-01-04
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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