The Dissociation Catastrophe in Fluctuating-Charge Models and its Implications for the Concept of Atomic Electronegativity
We have recently developed the QTPIE (charge transfer with polarization current equilibration) fluctuating-charge model, a new model with correct dissociation behavior for nonequilibrium geometries. The correct asymptotics originally came at the price of representing the solution in terms of charge-transfer variables instead of atomic charges. However, we have found an exact reformulation of fluctuating-charge models in terms of atomic charges again, which is made possible by the symmetries of classical electrostatics. We show how this leads to the distinction between two types of atomic electronegativities in our model. While one is a intrinsic property of individual atoms, the other takes into account the local electrical surroundings. This distinction could resolve some confusion surrounding the concept of electronegativity as to whether it is an intrinsic property of elements, or otherwise. We also use the QTPIE model to create a three-site water model and discuss simple applications.
KeywordsFluctuating charges Charge equilibration Electronegativity equalization Chemical hardness Force fields Molecular models Water models
Unable to display preview. Download preview PDF.
- 9.S. W. Rick, S. J. Stuart, in Reviews in Computational Chemistry, ed. by K. B. Lipkowitz, D. B. Boyd (Wiley, New York, 2002), Vol. 18Google Scholar
- 14.M. S. Gordon, L. Slipchenko, H. Li, J. H. Jensen, D. C. Spellmeyer, R. Wheeler, in Annual Reports in Computational Chemistry, ed. by D. C. Spellmeyer, R. A. Wheeler (Elsevier, Amsterdam, 2007), Vol. 3Google Scholar
- 23.L. Pauling, The Nature of the Chemical Bond, 2nd edition (Cornell University Press, Ithaca, NY, 1945)Google Scholar
- 40.R. W. Parr, W. Yang, Density-Functional Theory of Atoms and Molecules, 1st edition (Oxford, United Kingdom, 1989)Google Scholar
- 41.G. Del Re, J. Chem. Soc. 4031–4040 (1958)Google Scholar
- 48.D. R. Lide, CRC Handbook of Chemistry and Physics, 87 edition (CRC Press: Boca Raton, FL, 2006)Google Scholar
- 52.J. Nocedal, S. J. Wright, Numerical Optimization (Springer, New York, 2002)Google Scholar