Koopmans-compliant functionals and their performance against reference molecular data

Giovanni Borghi, Andrea Ferretti, Ngoc Linh Nguyen, Ismaila Dabo, Nicola Marzari

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

Koopmans-compliant functionals emerge naturally from extending the constraint of piecewise linearity of the total energy as a function of the number of electrons to each fractional orbital occupation. When applied to approximate density-functional theory, these corrections give rise to orbital-density-dependent functionals and potentials. We show that the simplest implementations of Koopmans' compliance provide accurate estimates for the quasiparticle excitations and leave the total energy functional almost or exactly intact, i.e., they describe correctly electron removals or additions, but do not necessarily alter the electronic charge density distribution within the system. Additional Koopmans-compliant functionals can be constructed that modify the potential energy surface, starting, e.g., from Perdew-Zunger corrections. These functionals become exactly one-electron self-interaction free and, as all Koopmans-compliant functionals, are approximately many-electron self-interaction free. We discuss in detail these different formulations, and provide extensive benchmarks for the 55 molecules in the reference G2-1 set, using Koopmans-compliant functionals constructed from local-density or generalized-gradient approximations. In all cases, we find excellent performance in the electronic properties, comparable or improved with respect to that of many-body perturbation theories, such as G0W0 and self-consistent GW, at a fraction of the cost and in a variational framework that also delivers energy derivatives. Structural properties and atomization energies preserve or slightly improve the accuracy of the underlying density-functional approximations.

Original languageEnglish (US)
Article number075135
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume90
Issue number7
DOIs
StatePublished - Aug 20 2014

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functionals
Electrons
Potential energy surfaces
Atomization
electrons
Charge density
Electronic properties
Density functional theory
Structural properties
orbitals
energy
atomizing
Derivatives
approximation
electronics
occupation
Molecules
linearity
density distribution
perturbation theory

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Borghi, Giovanni ; Ferretti, Andrea ; Nguyen, Ngoc Linh ; Dabo, Ismaila ; Marzari, Nicola. / Koopmans-compliant functionals and their performance against reference molecular data. In: Physical Review B - Condensed Matter and Materials Physics. 2014 ; Vol. 90, No. 7.
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Koopmans-compliant functionals and their performance against reference molecular data. / Borghi, Giovanni; Ferretti, Andrea; Nguyen, Ngoc Linh; Dabo, Ismaila; Marzari, Nicola.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 90, No. 7, 075135, 20.08.2014.

Research output: Contribution to journalArticle

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