Bond disproportionation, charge self-regulation, and ligand holes in s-p and in d -electron ABX 3 perovskites by density functional theory

Journal Article · Mon Aug 20 00:00:00 EDT 2018 · Physical Review. B

DOI:https://doi.org/10.1103/physrevb.98.075135· OSTI ID:1540937

Dalpian, G. M. ^[1]; Liu, Q. ^[2]; Varignon, J. ^[3]; Bibes, M. ^[3]; Zunger, Alex ^[2]

---

1. University of Colorado, Boulder, CO (United States); Universidade Federal do ABC, Sao Paulo (Brazil); DOE/OSTI
2. University of Colorado, Boulder, CO (United States)
3. University Paris-Saclay, Palaiseau (France)

Some ABX₃ perovskites exhibit different local environments (DLE) for the same B atoms in the lattice, an effect referred to as disproportionation, distinguishing such compounds from common perovskites that have single local environments (SLE). The basic phenomenology associated with such disproportionation involves the absence of B-atom charge ordering, the creation of different B-X bond length (“bond alternation”) for different local environments, the appearance of metal (in SLE) to insulator (in DLE) transitions, and the formation of ligand holes. We point out that this phenomenology is common to a broad range of chemical bonding patterns in ABX₃ compounds, either with s-p electron B-metal cations (BaBiO₃, CsTlF₃) or with noble-metal cations (CsAuCl₃), as well as with d-electron cations (SmNiO₃, CaFeO₃). Here we show that underlying much of this phenomenology is the “self-regulating response,” whereby in strongly bonded metal-ligand systems with high-lying ligand orbitals, the system protects itself from creating highly charged cations by transferring ligand electrons to the metal, thus preserving a nearly constant metal charge in different local environments, while creating B-ligand bond alternation and ligand-like conduction band (“ligand hole” states). We are asking what are the minimal theory ingredients needed to explain the main features of this SLE-to-DLE phenomenology, such as its energetic driving force, bond length changes, possible modifications in charge density, and density of state changes. Using as a guide the lowering of the total energy in DLE relative to SLE, we show that density functional calculations describe this phenomenology across the whole chemical bonding range without resort to special strong correlation effects, beyond what DFT naturally contains. In particular, lower total energy configurations (DLE) naturally develop bond alternation, gapping of the metallic SLE state, and absence of charge ordering with ligand hole formation.

• Research Organization: University of Colorado, Boulder, CO (United States)
• Sponsoring Organization: European Research Consolidator; National Council for Scientific and Technological Development (CNPq); Support Foundation to São Paulo State Research (FAPESP); USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE)
• Grant/Contract Number: AC02-05CH11231; SC0010467
• OSTI ID: 1540937
• Alternate ID(s): OSTI ID: 1465226
• Journal Information: Physical Review. B, Journal Name: Physical Review. B Journal Issue: 7 Vol. 98; ISSN 2469-9950
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
chemical bonding
crystal structure
density functional calculations
first-principles calculations
metal-insulator transition
perovskites