94 research outputs found
First principle electronic, structural, elastic, and optical properties of strontium titanate
We report self-consistent ab-initio electronic, structural, elastic, and
optical properties of cubic SrTiO perovskite. Our non-relativistic
calculations employed a generalized gradient approximation (GGA) potential and
the linear combination of atomic orbitals (LCAO) formalism. The distinctive
feature of our computations stem from solving self-consistently the system of
equations describing the GGA, using the Bagayoko-Zhao-Williams (BZW) method.
Our results are in agreement with experimental ones where the later are
available. In particular, our theoretical, indirect band gap of 3.24 eV, at the
experimental lattice constant of 3.91 \AA{}, is in excellent agreement with
experiment. Our predicted, equilibrium lattice constant is 3.92 \AA{}, with a
corresponding indirect band gap of 3.21 eV and bulk modulus of 183 GPa.Comment: 11 pages, 6 figures,Accepted for publication in AIP Advances (2012
First Principle Local Density Approximation Description of the Electronic Properties of Ferroelectric Sodium Nitrite
The electronic structure of the ferroelectric crystal, NaNO, is studied
by means of first-principles, local density calculations. Our ab-initio,
non-relativistic calculations employed a local density functional approximation
(LDA) potential and the linear combination of atomic orbitals (LCAO). Following
the Bagayoko, Zhao, Williams, method, as enhanced by Ekuma, and Franklin
(BZW-EF), we solved self-consistently both the Kohn-Sham equation and the
equation giving the ground state charge density in terms of the wave functions
of the occupied states. We found an indirect band gap of 2.83 eV, from W to R.
Our calculated direct gaps are 2.90, 2.98, 3.02, 3.22, and 3.51 eV at R, W, X,
{\Gamma}, and T, respectively. The band structure and density of states show
high localization, typical of a molecular solid. The partial density of states
shows that the valence bands are formed only by complex anionic states. These
results are in excellent agreement with experiment. So are the calculated
densities of states. Our calculated electron effective masses of 1.18, 0.63,
and 0.73 mo in the {\Gamma}-X, {\Gamma}-R, and {\Gamma}-W directions,
respectively, show the highly anisotropic nature of this material.Comment: 13 Pages, 4 Figures, and 2 Table
Re-examining the electronic structure of germanium: A first-principle study
We report results from an efficient, robust, ab-initio method for
self-consistent calculations of electronic and structural properties of Ge. Our
non-relativistic calculations employed a generalized gradient approximation
(GGA) potential and the linear combination of atomic orbitals (LCAO) formalism.
The distinctive feature of our computations stem from the use of
Bagayoko-Zhao-Williams-Ekuma-Franklin (BZW-EF) method. Our results are in
agreement with experimental ones where the latter are available. In particular,
our theoretical, indirect band gap of 0.65 eV, at the experimental lattice
constant of 5.66 \AA{}, is in excellent agreement with experiment. Our
predicted, equilibrium lattice constant is 5.63 \AA{}, with a corresponding
indirect band gap of 0.65 eV and a bulk modulus of 80 GPa. We also calculated
the effective masses in various directions with respect to the point.Comment: 10 Pages, 3 Figures, and 1 tabl
Local Density Approximation Description of Electronic Properties of Wurtzite Cadmium Sulfide (w-CdS)
We present calculated, electronic and related properties of wurtzite cadmium
sulfide (w-CdS). Our ab-initio, non-relativistic calculations employed a local
density functional approximation (LDA) potential and the linear combination of
atomic orbitals (LCAO). Following the Bagayoko, Zhao, and Williams (BZW)
method, we solved self-consistently both the Kohn-Sham equation and the
equation giving the ground state density in terms of the wave functions of the
occupied states. Our calculated, direct band gap of 2.47 eV, at the point, is
in excellent agreement with experiment. So are the calculated density of states
and the electron effective mass. In particular, our results reproduce the peaks
in the conduction band density of states, within the experimental
uncertainties.Comment: 22 Pages 4 Figure
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