Tight-binding Hamiltonian for LaOFeAs
First-principles electronic-structure calculations have been very useful in understanding some of the properties of the new iron-based superconductors. Further explorations of the role of the individual atomic orbitals in explaining various aspects of research in these materials, including experimental work, would benefit from the availability of a tight-binding (TB) Hamiltonian that accurately reproduces the first-principles band-structure results. In this work we have used the Naval Research Laboratory-TB method to construct a TB Hamiltonian from linearized augmented plane wave (LAPW) results. Our TB model includes the Fed orbitals and the p orbitals from both As and O for the prototype material LaOFeAs. The resulting TB band structure agrees well with that of the LAPW calculations from 2.7 eV below to 0.8 eV above the Fermi level, εF, and the Fermi surface matches perfectly to that of the LAPW. The TB densities of states (DOSs) are also in very good agreement with those from the LAPW in the above energy range, including the per orbital decomposition. We use our results to provide insights on the existence of a pseudogap in the DOS just above the Fermi level. We have also performed a separate TB fit to a database of LAPW results as a function of volume and with variations in the As positions. This fit although less accurate regarding the band structure near εF, reproduces the LAPW total energies very well and has transferability to nonfitted energies. © 2010 The American Physical Society.
Duke Scholars
Published In
DOI
EISSN
ISSN
Publication Date
Volume
Issue
Related Subject Headings
- Fluids & Plasmas
- 09 Engineering
- 03 Chemical Sciences
- 02 Physical Sciences
Citation
Published In
DOI
EISSN
ISSN
Publication Date
Volume
Issue
Related Subject Headings
- Fluids & Plasmas
- 09 Engineering
- 03 Chemical Sciences
- 02 Physical Sciences