title: Evaluating frontier orbital energy and HOMO/LUMO gap with descriptors from density functional reactivity theory.
abstract: Wave function theory (WFT) and density functional theory (DFT)-the two most popular solutions to electronic structure problems of atoms and molecules-share the same origin, dealing with the same subject yet using distinct methodologies. For example, molecular orbitals are artifacts in WFT, whereas in DFT, electron density plays the dominant role. One question that needs to be addressed when using these approaches to appreciate properties related to molecular structure and reactivity is if there is any link between the two. In this work, we present a piece of strong evidence addressing that very question. Using five polymeric systems as illustrative examples, we reveal that using quantities from DFT such as Shannon entropy, Fisher information, Ghosh-Berkowitz-Parr entropy, Onicescu information energy, Rényi entropy, etc., one is able to accurately evaluate orbital-related properties in WFT like frontier orbital energies and the HOMO (highest occupied molecular orbital)/LUMO (lowest unoccupied molecular orbital) gap. We verified these results at both the whole molecule level and the atoms-in-molecules level. These results provide compelling evidence suggesting that WFT and DFT are complementary to each other, both trying to comprehend the same properties of the electronic structure and molecular reactivity from different perspectives using their own characteristic vocabulary. Hence, there should be a bridge or bridges between the two approaches.
authors.affiliation: School of Pharmacy, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha, Hunan, 410081, China.
authors.forename: Chunying
authors.initials: C
authors.lastname: Rong
authors.affiliation: Department of Physics and Material Science and Center for Functional Photonics, City University of Hong Kong, Hong Kong, SAR, China. aprqz@cityu.edu.hk.
authors.forename: Ruiqin
authors.initials: R
authors.lastname: Zhang
authors.affiliation: Research Computing Center, University of North Carolina, Chapel Hill, NC, 27599-3420, USA. shubin@email.unc.edu.
authors.forename: Shubin
authors.initials: S
authors.lastname: Liu
keywords: Density functional reactivity theory; Fisher information; Frontier orbitals; HOMO/LUMO gap; Shannon entropy