Theoretical characterization of charge transport in chromia (α-Cr 2O 3)

N. Iordanova, Michel Dupuis, K. M. Rosso

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Transport of conduction electrons and holes through the lattice of α-Cr 2O 3 (chromia) is modeled as a valence alternation of chromium cations using ab initio electronic structure calculations and electron-transfer theory. In the context of the small polaron model, a cluster approach was used to compute quantities controlling the mobility of localized electrons and holes, i.e., the reorganization energy and the electronic coupling matrix element that enter Marcus' theory. The calculation of the electronic coupling followed the generalized Mulliken-Hush approach using the complete active space self-consistent-field (CASSCF) method and the quasidiabatic method. Our findings indicate that hole mobility is more than three orders of magnitude larger than electron mobility in both (001) and [001] lattice directions. The difference arises mainly from the larger internal reorganization energy calculated for electron-transport relative to hole-transport processes while electronic couplings have similar magnitudes. The much larger hole mobility versus electron mobility in α-Cr 2O 3 is in contrast to similar hole and electron mobilities in hematite α-Fe 2O 3 previously calculated. Our calculations also indicate that the electronic coupling for all charge-transfer processes of interest is smaller than for the corresponding processes in hematite. This variation is attributed to the weaker interaction between the metal 3d states and the O(2p) states in chromia than in hematite, leading to a smaller overlap between the charge-transfer donor and acceptor wave functions and smaller superexchange coupling in chromia. Nevertheless, the weaker coupling in chromia is still sufficiently large to suggest that charge-transport processes in chromia are adiabatic in nature. The electronic coupling is found to depend on both the superexchange interaction through the bridging oxygen atoms and the d-shell electron-spin coupling within the Cr-Cr donor-acceptor pair, while the reorganization energy is essentially independent of the electron-spin coupling.

Original languageEnglish
Article number074710
JournalJournal of Chemical Physics
Volume123
Issue number7
DOIs
Publication statusPublished - 2005

Fingerprint

Charge transfer
Hole mobility
Electron mobility
Electrons
hole mobility
hematite
electron mobility
electronics
Gene Conversion
Chromium
electron spin
Wave functions
Electronic structure
Cations
charge transfer
Metals
Oxygen
Atoms
alternations
internal energy

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

Theoretical characterization of charge transport in chromia (α-Cr 2O 3). / Iordanova, N.; Dupuis, Michel; Rosso, K. M.

In: Journal of Chemical Physics, Vol. 123, No. 7, 074710, 2005.

Research output: Contribution to journalArticle

@article{f5c8c159f4bf4b0b8b3058cd2266203a,
title = "Theoretical characterization of charge transport in chromia (α-Cr 2O 3)",
abstract = "Transport of conduction electrons and holes through the lattice of α-Cr 2O 3 (chromia) is modeled as a valence alternation of chromium cations using ab initio electronic structure calculations and electron-transfer theory. In the context of the small polaron model, a cluster approach was used to compute quantities controlling the mobility of localized electrons and holes, i.e., the reorganization energy and the electronic coupling matrix element that enter Marcus' theory. The calculation of the electronic coupling followed the generalized Mulliken-Hush approach using the complete active space self-consistent-field (CASSCF) method and the quasidiabatic method. Our findings indicate that hole mobility is more than three orders of magnitude larger than electron mobility in both (001) and [001] lattice directions. The difference arises mainly from the larger internal reorganization energy calculated for electron-transport relative to hole-transport processes while electronic couplings have similar magnitudes. The much larger hole mobility versus electron mobility in α-Cr 2O 3 is in contrast to similar hole and electron mobilities in hematite α-Fe 2O 3 previously calculated. Our calculations also indicate that the electronic coupling for all charge-transfer processes of interest is smaller than for the corresponding processes in hematite. This variation is attributed to the weaker interaction between the metal 3d states and the O(2p) states in chromia than in hematite, leading to a smaller overlap between the charge-transfer donor and acceptor wave functions and smaller superexchange coupling in chromia. Nevertheless, the weaker coupling in chromia is still sufficiently large to suggest that charge-transport processes in chromia are adiabatic in nature. The electronic coupling is found to depend on both the superexchange interaction through the bridging oxygen atoms and the d-shell electron-spin coupling within the Cr-Cr donor-acceptor pair, while the reorganization energy is essentially independent of the electron-spin coupling.",
author = "N. Iordanova and Michel Dupuis and Rosso, {K. M.}",
year = "2005",
doi = "10.1063/1.2007607",
language = "English",
volume = "123",
journal = "Journal of Chemical Physics",
issn = "0021-9606",
publisher = "American Institute of Physics Publising LLC",
number = "7",

}

TY - JOUR

T1 - Theoretical characterization of charge transport in chromia (α-Cr 2O 3)

AU - Iordanova, N.

AU - Dupuis, Michel

AU - Rosso, K. M.

PY - 2005

Y1 - 2005

N2 - Transport of conduction electrons and holes through the lattice of α-Cr 2O 3 (chromia) is modeled as a valence alternation of chromium cations using ab initio electronic structure calculations and electron-transfer theory. In the context of the small polaron model, a cluster approach was used to compute quantities controlling the mobility of localized electrons and holes, i.e., the reorganization energy and the electronic coupling matrix element that enter Marcus' theory. The calculation of the electronic coupling followed the generalized Mulliken-Hush approach using the complete active space self-consistent-field (CASSCF) method and the quasidiabatic method. Our findings indicate that hole mobility is more than three orders of magnitude larger than electron mobility in both (001) and [001] lattice directions. The difference arises mainly from the larger internal reorganization energy calculated for electron-transport relative to hole-transport processes while electronic couplings have similar magnitudes. The much larger hole mobility versus electron mobility in α-Cr 2O 3 is in contrast to similar hole and electron mobilities in hematite α-Fe 2O 3 previously calculated. Our calculations also indicate that the electronic coupling for all charge-transfer processes of interest is smaller than for the corresponding processes in hematite. This variation is attributed to the weaker interaction between the metal 3d states and the O(2p) states in chromia than in hematite, leading to a smaller overlap between the charge-transfer donor and acceptor wave functions and smaller superexchange coupling in chromia. Nevertheless, the weaker coupling in chromia is still sufficiently large to suggest that charge-transport processes in chromia are adiabatic in nature. The electronic coupling is found to depend on both the superexchange interaction through the bridging oxygen atoms and the d-shell electron-spin coupling within the Cr-Cr donor-acceptor pair, while the reorganization energy is essentially independent of the electron-spin coupling.

AB - Transport of conduction electrons and holes through the lattice of α-Cr 2O 3 (chromia) is modeled as a valence alternation of chromium cations using ab initio electronic structure calculations and electron-transfer theory. In the context of the small polaron model, a cluster approach was used to compute quantities controlling the mobility of localized electrons and holes, i.e., the reorganization energy and the electronic coupling matrix element that enter Marcus' theory. The calculation of the electronic coupling followed the generalized Mulliken-Hush approach using the complete active space self-consistent-field (CASSCF) method and the quasidiabatic method. Our findings indicate that hole mobility is more than three orders of magnitude larger than electron mobility in both (001) and [001] lattice directions. The difference arises mainly from the larger internal reorganization energy calculated for electron-transport relative to hole-transport processes while electronic couplings have similar magnitudes. The much larger hole mobility versus electron mobility in α-Cr 2O 3 is in contrast to similar hole and electron mobilities in hematite α-Fe 2O 3 previously calculated. Our calculations also indicate that the electronic coupling for all charge-transfer processes of interest is smaller than for the corresponding processes in hematite. This variation is attributed to the weaker interaction between the metal 3d states and the O(2p) states in chromia than in hematite, leading to a smaller overlap between the charge-transfer donor and acceptor wave functions and smaller superexchange coupling in chromia. Nevertheless, the weaker coupling in chromia is still sufficiently large to suggest that charge-transport processes in chromia are adiabatic in nature. The electronic coupling is found to depend on both the superexchange interaction through the bridging oxygen atoms and the d-shell electron-spin coupling within the Cr-Cr donor-acceptor pair, while the reorganization energy is essentially independent of the electron-spin coupling.

UR - http://www.scopus.com/inward/record.url?scp=34547648018&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=34547648018&partnerID=8YFLogxK

U2 - 10.1063/1.2007607

DO - 10.1063/1.2007607

M3 - Article

VL - 123

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 7

M1 - 074710

ER -