Journal article
Surface-Specific DFT + U Approach Applied to α-Fe2O3(0001)
Journal of physical chemistry. C, Vol.120(9), pp.4919-4930
03/10/2016
DOI: 10.1021/acs.jpcc.5b12144
Abstract
We report the bulk properties and ab initio thermodynamics surface free energies for α-Fe2O3(0001) using density functional theory (DFT) with calculated Hubbard U values for chemically distinct surface Fe atoms. There are strong electron correlation effects in hematite that are not well-described by standard DFT. A better description can be achieved by using a DFT + U approach in which U represents a Hubbard on-site Coulomb repulsion term. While DFT + U calculations result in improved predictions of the bulk hematite band gap, surface free energies using DFT + U total energies result in surface structure predictions that are at odds with most experimental results. Specifically, DFT + U predictions stabilize a ferryl termination relative to an oxygen termination that is widely reported under a range of experimental conditions. We explore whether treating chemically distinct surface Fe atoms with different U values can lead to improved bulk and surface predictions. We use a linear response technique to derive specific Ud values for all Fe atoms in several slab geometries. We go on to add a Coulomb correction, Up, to better describe the hybridization between the Fe d and oxygen p orbitals, accurately predicting the structural and electronic properties of bulk hematite. Our results show that the site-specific Ud is a key factor in obtaining theoretical results for surface stability that are congruent with the experimental literature results of α-Fe2O3(0001) surface structure. Finally, we use a model surface reaction to trace how the various DFT + U methods affect the surface electronic structure and heterogeneous reactivity.
Details
- Title: Subtitle
- Surface-Specific DFT + U Approach Applied to α-Fe2O3(0001)
- Creators
- Xu HuangSai Kumar RamaduguSara E Mason
- Resource Type
- Journal article
- Publication Details
- Journal of physical chemistry. C, Vol.120(9), pp.4919-4930
- DOI
- 10.1021/acs.jpcc.5b12144
- NLM abbreviation
- J Phys Chem C Nanomater Interfaces
- ISSN
- 1932-7447
- eISSN
- 1932-7455
- Publisher
- American Chemical Society
- Grant note
- DOI: 10.13039/100000086, name: Directorate for Mathematical and Physical Sciences, award: CHE-1254127
- Language
- English
- Date published
- 03/10/2016
- Academic Unit
- Chemistry; ITS Research Services
- Record Identifier
- 9983985925602771
Metrics
42 Record Views