Numerous density functional theory (DFT) methods have been developed in recent years to reliably describe the entire spectrum of non-covalent interactions.  A wide range of these DFT techniques has been employed to compute the structures, energetics and harmonic vibrational frequencies of some fairly simple non-covalent complexes.  The results are compared to data from MP2 and CCSD(T) computations.  As expected, many modern DFT methods provide very reliable energetics and structures.  In many cases, however, there are some rather significant discrepancies from the vibrational frequency computations.  Most notably, we continue to encounter discrepancies in the Hessian index (or number of imaginary vibrational frequencies) for many stationary points, including some minima.

Vibrational frequencies of non-covalent clusters from DFT, MP2, and CCSD(T) computations: Some disconcerting discrepancies

248th National Meeting (2014)

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