Theory of ionization potentials of nonmetallic solids

Yu Kumagai, Keith T. Butler, Aron Walsh, Fumiyasu Oba

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Since the ionization potential (IP) is one of the fundamental quantities in a solid, ruling the physical and chemical properties and electronic device performances, many researchers have quantified the IPs using first-principles calculations of slab models recently. However, the breakdown into bulk and surface contributions has remained a contentious issue. In this study, we discuss how to decompose the IP into the bulk and surface contributions by using the macroscopic average technique. Although this procedure quantifies well-defined macroscopic dipoles and corroborates with the continuous model, it is not consistent with the physical intuition. This is because the strong charge fluctuation inside solids significantly contributes to the macroscopic dipole potential. We also discuss the possibility of an alternative splitting procedure that can be consistent with the physical intuition, and conclude that it is possible only when both bulk and surface charge density is well decomposed into a superposition of spherical charges. In the latter part, we evaluate the IPs of typical semiconductors and insulators such as Si, diamond, GaAs, GaN, ZnO, and MgO, using atomic-charge and molecular-charge approximations, in which the charge density of a solid is described as a superposition of charge density of the constituent atoms and molecules, respectively. We find that the atomic-charge approximation also known as the model-solid theory can successfully reproduce the IPs of covalent materials, but works poorly for ionic materials. On the other hand, the molecular-charge approximation, which partly takes into account the charge transfer from cations to anions, shows better predictive performance overall.

Original languageEnglish
Article number125309
JournalPhysical Review B
Volume95
Issue number12
DOIs
Publication statusPublished - 2017 Mar 14

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Ionization potential
ionization potentials
Charge density
approximation
dipoles
Diamond
Surface charge
chemical properties
Chemical properties
Anions
Cations
Charge transfer
Diamonds
slabs
Negative ions
Physical properties
physical properties
breakdown
Positive ions
diamonds

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Kumagai, Yu ; Butler, Keith T. ; Walsh, Aron ; Oba, Fumiyasu. / Theory of ionization potentials of nonmetallic solids. In: Physical Review B. 2017 ; Vol. 95, No. 12.
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Theory of ionization potentials of nonmetallic solids. / Kumagai, Yu; Butler, Keith T.; Walsh, Aron; Oba, Fumiyasu.

In: Physical Review B, Vol. 95, No. 12, 125309, 14.03.2017.

Research output: Contribution to journalArticle

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