B. Khamala | University of Texas at El Paso (UTEP) (original) (raw)
Uploads
Papers by B. Khamala
We report calculated, electronic and related properties of wurtzite and zinc blende gallium nitri... more We report calculated, electronic and related properties of wurtzite and zinc blende gallium nitrides (w-GaN, zb-GaN). We employed a local density approximation (LDA) potential and the linear combination of atomic orbital (LCAO) formalism. The implementation of this formalism followed the Bagayoko, Zhao, and Williams (BZW) method, as enhanced by Ekuma and Franklin (BZW-EF). The calculated electronic and related properties, for both structures of GaN, are in good agreement with corresponding, experimental data, unlike results from most previous ab initio calculations utilizing a density functional theory (DFT) potential. These results include the electronic energy bands, the total and partial densities of states (DOS and pDOS), and effective masses for both structures. The calculated band gap of 3.29 eV, for w-GaN, is in agreement with experiment and is an average of 1.0 eV larger than most previous ab-initio DFT results. Similarly, the calculated band gap of zb-GaN of 2.9 eV, for a r...
Following an introduction, we briefly recall the derivation of density functional theory (DFT) an... more Following an introduction, we briefly recall the derivation of density functional theory (DFT) and of its local density approximation (LDA). It follows from this derivation that eigenvalues resulting from self consistent DFT calculations utilizing a single input basis set do not necessarily have much physical content. We present necessary conditions for their greatest physical content. We subsequently note new results from self consistent DFT calculations that agree very well with corresponding experimental ones. The latter calculations utilized the Bagayoko, Zhao, and Williams (BZW) method as enhanced by Ekuma and Franklin (BZW-EF). We show that the excellent agreement is due to the inherent and accurate physical content of results from self consistent BZW-EF calculations that strictly adhere to intrinsic requirements (conditions) germane to DFT. We describe the mathematical artifact that affects unoccupied energies when basis sets much larger than the DFT-optimal one are utilized to study materials with energy or band gaps.
We report calculated, electronic and related properties of wurtzite and zinc blende gallium nitri... more We report calculated, electronic and related properties of wurtzite and zinc blende gallium nitrides (w-GaN, zb-GaN). We employed a local density approximation (LDA) potential and the linear combination of atomic orbital (LCAO) formalism. The implementation of this formalism followed the Bagayoko, Zhao, and Williams (BZW) method, as enhanced by Ekuma and Franklin (BZW-EF). The calculated electronic and related properties, for both structures of GaN, are in good agreement with corresponding, experimental data, unlike results from most previous ab initio calculations utilizing a density functional theory (DFT) potential. These results include the electronic energy bands, the total and partial densities of states (DOS and pDOS), and effective masses for both structures. The calculated band gap of 3.29 eV, for w-GaN, is in agreement with experiment and is an average of 1.0 eV larger than most previous ab-initio DFT results. Similarly, the calculated band gap of zb-GaN of 2.9 eV, for a r...
Following an introduction, we briefly recall the derivation of density functional theory (DFT) an... more Following an introduction, we briefly recall the derivation of density functional theory (DFT) and of its local density approximation (LDA). It follows from this derivation that eigenvalues resulting from self consistent DFT calculations utilizing a single input basis set do not necessarily have much physical content. We present necessary conditions for their greatest physical content. We subsequently note new results from self consistent DFT calculations that agree very well with corresponding experimental ones. The latter calculations utilized the Bagayoko, Zhao, and Williams (BZW) method as enhanced by Ekuma and Franklin (BZW-EF). We show that the excellent agreement is due to the inherent and accurate physical content of results from self consistent BZW-EF calculations that strictly adhere to intrinsic requirements (conditions) germane to DFT. We describe the mathematical artifact that affects unoccupied energies when basis sets much larger than the DFT-optimal one are utilized to study materials with energy or band gaps.