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Title: Density-functional errors in ionization potential with increasing system size

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.

Authors:
; ;  [1];  [1];  [2]
  1. Chemistry and Chemical Biology, School of Natural Sciences, University of California, Merced, 5200 North Lake Road, Merced, California 95343 (United States)
  2. (Canada)
Publication Date:
OSTI Identifier:
22415762
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 142; Journal Issue: 18; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ALKANES; ALKENES; DENSITY FUNCTIONAL METHOD; FUNCTIONALS; IONIZATION POTENTIAL; MOLECULES; PERFORMANCE; POTENTIALS

Citation Formats

Whittleton, Sarah R., Sosa Vazquez, Xochitl A., Isborn, Christine M., E-mail: cisborn@ucmerced.edu, Johnson, Erin R., E-mail: erin.johnson@dal.ca, and Department of Chemistry, Dalhousie University, 6274 Coburg Road, Halifax, Nova Scotia B3H 4R2. Density-functional errors in ionization potential with increasing system size. United States: N. p., 2015. Web. doi:10.1063/1.4920947.
Whittleton, Sarah R., Sosa Vazquez, Xochitl A., Isborn, Christine M., E-mail: cisborn@ucmerced.edu, Johnson, Erin R., E-mail: erin.johnson@dal.ca, & Department of Chemistry, Dalhousie University, 6274 Coburg Road, Halifax, Nova Scotia B3H 4R2. Density-functional errors in ionization potential with increasing system size. United States. doi:10.1063/1.4920947.
Whittleton, Sarah R., Sosa Vazquez, Xochitl A., Isborn, Christine M., E-mail: cisborn@ucmerced.edu, Johnson, Erin R., E-mail: erin.johnson@dal.ca, and Department of Chemistry, Dalhousie University, 6274 Coburg Road, Halifax, Nova Scotia B3H 4R2. Thu . "Density-functional errors in ionization potential with increasing system size". United States. doi:10.1063/1.4920947.
@article{osti_22415762,
title = {Density-functional errors in ionization potential with increasing system size},
author = {Whittleton, Sarah R. and Sosa Vazquez, Xochitl A. and Isborn, Christine M., E-mail: cisborn@ucmerced.edu and Johnson, Erin R., E-mail: erin.johnson@dal.ca and Department of Chemistry, Dalhousie University, 6274 Coburg Road, Halifax, Nova Scotia B3H 4R2},
abstractNote = {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.},
doi = {10.1063/1.4920947},
journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 18,
volume = 142,
place = {United States},
year = {2015},
month = {5}
}