INFIQC   05475
INSTITUTO DE INVESTIGACIONES EN FISICO- QUIMICA DE CORDOBA
Unidad Ejecutora - UE
artículos
Título:
Accurate Electron Affinities and Orbital Energies of Anions from a Non-Empirically Tuned Range-Separated DFT Approach
Autor/es:
MARÍA BELÉN OVIEDO; LINDSEY N. ANDERSON; BRYAN M. WONG
Revista:
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
Editorial:
AMER CHEMICAL SOC
Referencias:
Lugar: Washington; Año: 2017
ISSN:
1549-9618
Resumen:
The treatment of atomic anions with Kohn-Sham density functional theory (DFT) has long been controversial since the highest occupied molecular orbital (HOMO) energy, EHOMO, is often calculated to be positive with most approximate density functionals. We assess the accuracy of orbital energies and electron affinities for all three rows of elements in the periodic table (H-Ar) using a variety of theoretical approaches and customized basis sets. Among all of the theoretical methods studied here, we find that a non-empirically tuned range-separated approach (constructed to satisfy DFT-Koopmans? theorem for the anionic electron system) provides the best accuracy for a variety of basis sets ? even for small basis sets where most functionals typically fail. Previous approaches to solve this conundrum of positive EHOMO values have utilized non-self-consistent methods; however electronic properties, such as electronic couplings/gradients (which require a self-consistent potential and energy), become ill-defined with these approaches. In contrast, the non-empirically tuned range-separated procedure yields well-defined electronic couplings/gradients and correct EHOMO values since both the potential and resulting electronic energy are computed self-consistently. Orbital energies and electron affinities are further analyzed in the context of the electronic energy as a function of electronic number (including fractional numbers of electrons) to provide a stringent assessment of self-interaction errors for these complex anion systems.