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Accurate, First-Principle Study of Electronic and Related Properties of the Ground State of Li<sub>2</sub>Se 预览
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作者 Abdoulaye Goita Feng Gao +3 位作者 Ifeanyi H. Nwigboji Yuriy Malozovsky Lashounda Franklin Diola Bagayoko 《现代物理(英文)》 2019年第8期909-921,共13页
We present results from ab-initio, self-consistent calculations of electronic and related properties for the ground state of cubic lithium selenide (Li2Se). We employed a local density approximation (LDA) potential an... We present results from ab-initio, self-consistent calculations of electronic and related properties for the ground state of cubic lithium selenide (Li2Se). We employed a local density approximation (LDA) potential and performed computations following the Bagayoko, Zhao, and Williams (BZW) method, as enhanced by Ekuma and Franklin (BZW-EF). This method verifiably leads to the ground state of materials without employing over-complete basis sets. We present the calculated electronic energies, total and partial densities of states, effective masses, and the bulk modulus. The present calculated band structures show clearly that cubic Li2Se has a direct fundamental energy band gap of 4.065 eV at the &Gamma;point for the room temperature experimental lattice constant of 6.017 &Aring;. This result is different from findings of previous density functional theory (DFT) calculations that uniformly reported an indirect band gap, from &Gamma;to X, for Li2Se. We predicted a direct band gap of 4.363 eV, at the computationally determined equilibrium lattice constant of 5.882 &Aring;, and a bulk modulus of 35.4 GPa. For the first time known to us, we report calculated electron and hole effective masses for Li2Se. The experimental confirmation of the large, direct gap we found will point to a potential importance of this material for ultraviolet technologies and applications. Due to a lack of experimental results, most of our calculated ones in this paper are predictions for Li2Se. 展开更多
关键词 Density Functional Theory BZW-EF Method ELECTRONIC Properties Bulk MODULUS
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Predictions of Electronic, Transport, and Structural Properties of Magnesium Sulfide (MgS) in the Rocksalt Structure 预览
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作者 Uttam Bhandari Cheick Oumar Bamba +2 位作者 Yuriy Malozovsky La Shounda Franklin Diola Bagayoko 《现代物理(英文)》 2018年第9期1773-1784,共12页
We report results from ab-initio, self-consistent density functional theory (DFT) calculations of electronic, transport and bulk properties of rock salt magnesium sulfide (MgS). In the absence of experimental data on ... We report results from ab-initio, self-consistent density functional theory (DFT) calculations of electronic, transport and bulk properties of rock salt magnesium sulfide (MgS). In the absence of experimental data on these properties, except for the bulk modulus, these results are predictions. Our calculations utilized the Ceperley and Alder local density approximation (LDA) potential and the linear combination of Gaussian orbitals (LCGO). The key difference between our computations and other previous ab-initio DFT ones stems from our use of successively larger basis sets, in consecutive, self-consistent calculations, to attain the ground state of the material. We predicted an indirect (&Gamma;-X) band gap of 3.278 eV for a room temperature lattice constant of 5.200&Aring;. We obtained a predicted low temperature indirect (&Gamma;-X) band gap of 3.512 eV, using the equilibrium lattice constant of 5.183&Aring;. We found a theoretical value of 79.76 GPa for the bulk modulus;it agrees very well with the experimental finding of 78 &plusmn;3.7 GPa. 展开更多
关键词 DENSITY Functional Theory (DFT) Local DENSITY Approximation (LDA) Linear Combination of Atomic ORBITALS (LCAO) BAND Gap BAND Structure The Bagayoko ZHAO and WILLIAMS (BZW) Method
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<i>Ab-Initio</i>Computations of Electronic, Transport, and Related Properties of Chromium Disilicide (CrSi<sub>2</sub>) 预览
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作者 Shaibu Onuche Mathias Yuriy Malozovsky +1 位作者 Lashounda Franklin Diola Bagayoko 《现代物理(英文)》 2018年第14期2457-2472,共16页
We report results from ab-initio, self-consistent density functional theory (DFT) calculations of electronic, transport, and related properties of chromium disilicide (CrSi2) in the hexagonal C40 crystal structure. Ou... We report results from ab-initio, self-consistent density functional theory (DFT) calculations of electronic, transport, and related properties of chromium disilicide (CrSi2) in the hexagonal C40 crystal structure. Our computations utilized the Ceperley and Alder local density approximation (LDA) potential and the linear combination of atomic orbitals (LCAO) formalism. As required by the second DFT theorem, our calculations minimized the occupied energies, far beyond the minimization obtained with self-consistency iterations with a single basis set. Our calculated, indirect band gap is 0.313 eV, at room temperature (using experimental lattice constants of a = 4.4276? and c = 6.368 ). We discuss the energy bands, total and partial densities of states, and electron and hole effective masses. This work was funded in part by the US Department of Energy, National Nuclear Security Administration (NNSA) (Award No. DE-NA0003679), the National Science Foundation (NSF) (Award No. HRD-1503226), LaSPACE, and LONI-SUBR. 展开更多
关键词 BAND Gap BZW-EF Method Density Functional Theory BAND Structure CrSi2
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Accurate Electronic, Transport, and Related Properties of Wurtzite Beryllium Oxide (w-BeO) 预览
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作者 Cheick Oumar Bamba Richard Inakpenu +4 位作者 Yacouba I. Diakite Lashounda Franklin Yuriy Malozovsky Anthony D. Stewart Diola Bagayoko 《现代物理(英文)》 2017年第12期1938-1949,共12页
We report details of our ab-initio, self-consistent density functional theory (DFT) calculations of electronic and related properties of wurtzite beryllium oxide (w-BeO). Our calculations were performed using a local ... We report details of our ab-initio, self-consistent density functional theory (DFT) calculations of electronic and related properties of wurtzite beryllium oxide (w-BeO). Our calculations were performed using a local density approximation (LDA) potential and the linear combination of atomic orbitals (LCAO) formalism. Unlike previous DFT studies of BeO, the implementation of the Bagayoko, Zhao, and Williams (BZW) method, as enhanced by the work of Ekuma and Franklin (BZW-EF), ensures the full physical content of the results of our calculations, as per the derivation of DFT. We present our computed band gap, total and partial densities of states, and effective masses. Our direct band gap of 10.30 eV, reached by using the experimental lattice constants of a = 2.6979 &Aring;and c = 4.3772 &Aring;at room temperature, agrees very well the experimental values of 10.28 eV and 10.3 eV. The hybridization of O and Be p states in the upper valence bands, as per our calculated, partial densities of states, are in agreement with corresponding, experimental findings. 展开更多
关键词 Density Functional Theory BZW-EF Method ACCURATE Calculated Properties
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Accurate Electronic, Transport, and Bulk Properties of Zinc Blende Gallium Arsenide (Zb-GaAs) 预览
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作者 Yacouba Issa Diakite Sibiri D. Traore +3 位作者 Yuriy Malozovsky Bethuel Khamala Lashounda Franklin Diola Bagayoko 《现代物理(英文)》 2017年第4期531-546,共16页
We report accurate, calculated electronic, transport, and bulk properties of zinc blende gallium arsenide (GaAs). Our ab-initio, non-relativistic, self-con-sistent calculations employed a local density approximation (... We report accurate, calculated electronic, transport, and bulk properties of zinc blende gallium arsenide (GaAs). Our ab-initio, non-relativistic, self-con-sistent calculations employed a local density approximation (LDA) potential and the linear combination of atomic orbital (LCAO) formalism. We strictly followed the Bagayoko, Zhao, and William (BZW) method, as enhanced by Ekuma and Franklin (BZW-EF). Our calculated, direct band gap of 1.429 eV, at an experimental lattice constant of 5.65325 &Aring;, is in excellent agreement with the experimental values. The calculated, total density of states data reproduced several experimentally determined peaks. We have predicted an equilibrium lattice constant, a bulk modulus, and a low temperature band gap of 5.632 &Aring;, 75.49 GPa, and 1.520 eV, respectively. The latter two are in excellent agreement with corresponding, experimental values of 75.5 GPa (74.7 GPa) and 1.519 eV, respectively. This work underscores the capability of the local density approximation (LDA) to describe and to predict accurately properties of semiconductors, provided the calculations adhere to the conditions of validity of DFT. 展开更多
关键词 Density Functional Theory BZW-EF Method ELECTRONIC Properties Band Gap Predictions GALLIUM ARSENIDE
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<i>Ab-Initio</i>Computations of Electronic, Transport, and Structural Properties of <i>zinc-blende</i>Beryllium Selenide (<i>zb</i>-BeSe) 预览
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作者 Richard Inakpenu Cheick Bamba +4 位作者 Ifeanyi H. Nwigboji Lashounda Franklin Yuriy Malozovsky Guang-Lin Zhao Diola Bagayoko 《现代物理(英文)》 2017年第4期552-566,共15页
We report results from several ab-initio computations of electronic, transport and bulk properties of zinc-blende beryllium selenide (zb-BeSe). Our nonrelativistic calculations utilized a local density approximation (... We report results from several ab-initio computations of electronic, transport and bulk properties of zinc-blende beryllium selenide (zb-BeSe). Our nonrelativistic calculations utilized a local density approximation (LDA) potential and the linear combination of atomic orbitals (LCAO). The key distinction of our calculations from other DFT calculations is the implementation of the Bagayoko, Zhao and Williams (BZW) method, as enhanced by Ekuma and Franklin (BZW-EF), in the LCAO formalism. Our calculated, indirect band gap is 5.46 eV, from &Gamma;to a conduction band minimum between Г and X, for a room temperature lattice constant of 5.152 &Aring;. Available, room temperature experimental band gaps of 5.5 (direct) and 4 - 4.5 (unspecified) point to the need for additional measurements of this gap. Our calculated bulk modulus of 92.35 GPa is in excellent agreement with experiment (92.2 &plusmn;?1.8 GPa). Our predicted equilibrium lattice constant and band gap, at zero temperature, are 5.0438 &Aring;and 5.4 eV, respectively. 展开更多
关键词 Density Functional Theory (DFT) LDA Ab-Initio Calculations Band Gap BZW-EF Method
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