Andrew Pudzianowski - A Systematic Appraisal of Density Functional Methodologies for Hydrogen Bonding in Binary Ionic Complexes

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      Pudzianowski, Andrew T. The Journal of Physical   Chemistry 1996 100 (12) 4781-4789

      Abstract: A number of density functional (DF)   methodologies were systematically examined for their ability to   describe strong hydrogen bonds. A set of 10 ion/molecule systems,   5 cationic and 5 anionic, was chosen on the basis of the   availability of experimental and high-level ab initio results   against which the DF methods could be compared. All DF models   used the Lee−Yang−Parr (LYP) functional for nonlocal electron   correlation, and either the 1988 Becke (B) or 1993 Becke   “three-parameter” (B3) nonlocal exchange functional. Full   geometry optimizations were carried out with the B-LYP   combination and Gaussian basis sets, including Pople bases from   6-31G(d,p) to 6-311++G(d,p), and the TZVP and TZVP+ bases, as   well as with the numerical DMol DNP and DNPP basis sets, but   B3-LYP was used only with 6-311++G(d,p). Vibrational modes and   thermodynamic functions were calculated only with the B-LYP/ and   B3-LYP/6-311++G(d,p) models. The results support the following   major conclusions. Nonlocal DF models require diffuse atomic   functions to adequately describe strong H-bonding systems,   especially in anionic complexes. With 6-311++G(d,p) the B-LYP and   B3-LYP models are slightly inferior, but still quite similar, to   MP2. B3-LYP is clearly the better DF model, yielding complexation   enthalpies with root mean square deviations of 0.7 and 1.6   kcal/mol, respectively, from the MP2 and experimental values.   More satisfactory agreement with experiment can be obtained in   individual cases by judicious enlargement of the basis set.   Efficient auxiliary basis/model density DF methods are much   faster than ex post facto DF schemes based on existing ab initio   methodology, which in turn are appreciably faster than MP2 with   the same basis set. DF models of good quality will extend to   strong H-bonded systems large enough to be of direct bioorganic   relevance.

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