Ab-initio structural and electronic properties of Fe, Si, GaAs and NiO from a novel DFT+U+V approach
Abstract
The electronic and structural properties of materials as diverse as Fe, Si, GaAs and NiO are investigated using a novel DFT+U energy functional named DFT+U+V. In this approach the corrective ("+U") Hamiltonian is constructed on an extended Hubbard model that includes both on-site (U) and inter-site (V) electron-electron interactions. The competition between these interaction parameters avoids the over-stabilization of filled atomic orbitals that is usually observed with the "standard" DFT+U approach and allows to describe systems (like covalent semiconductors) whose valence electrons are "localized" on hybridized orbitals (bonds) rather than on pure atomic states. Thus the novel DFT+U+V functional not only improves significantly the energetics (crucial for performing structural optimizations and studying phase transitions) but also dramatically extends the applicability of the "standard" DFT+U to a much broader class of systems. Also, the additional inter-site interaction parameter V can be straightforwadly obtained (at no additional cost) from the same linear-response approach used to calculate U [1]. The effectiveness and reliability of the novel functional are demonstrated by the good results obtained with semiconductor (Si and GaAs)and charge-transfer insulator (NiO) materials. Some still remaining difficulties with metals are also discussed. [1] M. Cococcioni and S. de Gironcoli, Phys. Rev. B 71, 035105 (2005).
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFMMR21B1779C
- Keywords:
-
- 3909 Elasticity and anelasticity;
- 3914 Electrical properties;
- 3919 Equations of state;
- 3924 High-pressure behavior