Density-functional errors in ionization potential with increasing system size

Whittleton, Sarah R.; Sosa Vazquez, Xochitl A.

doi:10.1063/1.4920947

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Density-functional errors in ionization potential with increasing system size

Whittleton, Sarah R.·Sosa Vazquez, Xochitl A.

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Abstract

This work investigates the effects of molecular size on the accuracy of density-functional ionization potentials for a set of 28 hydrocarbons, including series of alkanes, alkenes, and oligoacenes. As the system size increases, delocalization error introduces a systematic underestimation of the ionization potential, which is rationalized by considering the fractional-charge behavior of the electronic energies. The computation of the ionization potential with many density-functional approximations is not size-extensive due to excessive delocalization of the incipient positive charge. While inclusion of exact exchange reduces the observed errors, system-specific tuning of long-range corrected functionals does not generally improve accuracy. These results emphasize that good performance of a functional for small molecules is not necessarily transferable to larger systems.

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY ALKANES ALKENES DENSITY FUNCTIONAL METHOD FUNCTIONALS IONIZATION POTENTIAL MOLECULES PERFORMANCE POTENTIALS

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Whittleton, Sarah R., Sosa Vazquez, Xochitl A.. 2015-05-14. Density-functional errors in ionization potential with increasing system size. https://doi.org/10.1063/1.4920947

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