Ab initio Electronic Band Structure Calculations for Beryllium Chalcogenides

1998 ◽  
Vol 12 (19) ◽  
pp. 1975-1984 ◽  
Author(s):  
G. Kalpana ◽  
G. Pari ◽  
A. Mookerjee ◽  
A. K. Bhattacharyya
Keyword(s):  
Bulk Modulus ◽  
Band Gap ◽  
Structural Transition ◽  
Electronic Band Structure ◽  
Local Density ◽  
Structural Phase ◽  
Experimental Results ◽  
Orbital Method ◽  
Electronic Band ◽  
Indirect Band Gap

The first principles tight-binding linear muffin-tin orbital method within the local density approximation (LDA) has been used to calculate the ground state properties structural phase transition and pressure dependence of the band gap of BeS, BeSe and BeTe. We have calculated the energy-volume relations for these compounds in the B3 and B8 phases. The calculated lattice parameters, bulk modulus and the pressure-volume relation were found to be in good agreement with the recent experimental results. We have also calculated the cohesive energy for them and they are consistent with the bulk modulus. The calculated B3 to B8 structural transition pressure for BeS, BeS and BeTe agree well with the experimental results. Our calculations show that these compounds are indirect band gap (Γ-X) semiconductors at ambient conditions. The calculated band gap values are found to be underestimated by 20–30% which is due to the usage of LDA. After the structural transition to the B8 phase BeS continues to be indirect band gap semiconductor and ultimately it becomes metallic above 100 GPa. BeSe and BeTe are metallic at B3 to B8 structural transition.

Structural, electronic and elastic properties of the B2-ScM (M =Au, Hg and Tl) intermetallic compounds: Ab initio calculations

2015 ◽  
Vol 04 (04) ◽  
pp. 1550020
Author(s):  
Ahmad A. Mousa ◽  
Jamil M. Khalifeh
Keyword(s):  
Mechanical Properties ◽  
Bulk Modulus ◽  
Intermetallic Compounds ◽  
Elastic Constants ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Local Density ◽  
Full Potential ◽  
Generalized Gradient ◽  
Electronic Band

Structural, electronic, elastic and mechanical properties of ScM (M[Formula: see text][Formula: see text][Formula: see text]Au, Hg and Tl) intermetallic compounds are studied using the full potential-linearized augmented plane wave (FP-LAPW) method based on the density functional theory (DFT), within the generalized gradient approximation (GGA) and the local density approximation (LDA) to the exchange-correlation approximation energy as implemented in the Wien2k code. The ground state properties including lattice parameters, bulk modulus and elastic constants were all computed and compared with the available previous theoretical and experimental results. The lattice constant was found to increase in contrast to the bulk modulus which was found to decrease with every substitution of the cation (M) starting from Au till Tl in ScM. Both the electronic band structure and density-of-states (DOS) calculations show that these compounds possess metallic properties. The calculated elastic constants ([Formula: see text], [Formula: see text] and [Formula: see text] confirmed the elastic stability of the ScM compounds in the B2-phase. The mechanical properties and ductile behaviors of these compounds are also predicted based on the calculated elastic constants.

scholarly journals Structural, Electronic and Vibrational Properties of YAl3(BO3)4

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 545 ◽  
Author(s):  
Aleksandr S. Oreshonkov ◽  
Evgenii M. Roginskii ◽  
Nikolai P. Shestakov ◽  
Irina A. Gudim ◽  
Vladislav L. Temerov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Band Gap ◽  
Density Functional ◽  
Dielectric Material ◽  
Electronic Band Structure ◽  
Vibrational Properties ◽  
Electronic Band ◽  
Functional Theory ◽  
Dynamical Properties ◽  
Indirect Band Gap

The crystal structure of YAl3(BO3)4 is obtained by Rietveld refinement analysis in the present study. The dynamical properties are studied both theoretically and experimentally. The experimental Raman and Infrared spectra are interpreted using the results of ab initio calculations within density functional theory. The phonon band gap in the Infrared spectrum is observed in both trigonal and hypothetical monoclinic structures of YAl3(BO3)4. The electronic band structure is studied theoretically, and the value of the band gap is obtained. It was found that the YAl3(BO3)4 is an indirect band gap dielectric material.

Electronic Band Structure of Cubic Silicon Carbide Nanowires

2008 ◽  
Vol 600-603 ◽  
pp. 575-578 ◽  
Author(s):  
A. Miranda ◽  
A. Estrella Ramos ◽  
M. Cruz Irisson
Keyword(s):  
Silicon Carbide ◽  
Band Structure ◽  
Band Gap ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Local Density ◽  
Thickness Variation ◽  
Hydrogen Atoms ◽  
Electronic Band ◽  
Cubic Silicon Carbide

In this work, the effects of the diameter and morphology on the electronic band structure of hydrogenated cubic silicon carbide (b-SiC) nanowires is studied by using a semiempirical sp3s* tight-binding (TB) approach applied to the supercell model, where the Si- and C-dangling bonds on the surface are passivated by hydrogen atoms. Moreover, TB results (for the bulk) are compared with density functional calculations in the local density approximation. The results show that though surface morphology modifies the band gap, the change is more systematic with the thickness variation. As expected, hydrogen saturation induces a broadening of the band gap energy because of the quantum confinement effect.

STRUCTURAL PHASE TRANSITION, ELASTIC AND ELECTRONIC PROPERTIES OF CuXSe2(X = In, Ga) CHALCOPYRITE

2012 ◽  
Vol 19 (02) ◽  
pp. 1250021 ◽  
Author(s):  
T. BOUGUETAIA ◽  
B. ABIDRI ◽  
B. BENBAHI ◽  
D. RACHED ◽  
S. HIADSI ◽  
...  
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Local Density ◽  
Structural Phase ◽  
Theoretical Data ◽  
Young Modulus ◽  
Orbital Method ◽  
Full Potential ◽  
Direct Band

The structural, elastic and electronic properties of chalcopyrite compound CuInSe2 and CuGaSe2 have been investigated using the full-potential linearized muffin-tin orbital method (FP-LMTO) within the frame of density functional theory (DFT). In this approach, the local density approximation is used for the exchange-correlation potential using Perdew–Wang parametrization. The equilibrium lattice parameters, bulk modulus, transition pressure, elastic constants and their related parameters such as Poisson's ratio, Young modulus, shear modulus and Debye temperature were calculated and compared with available experimental and theoretical data. They are in reasonable agreement. In this paper the electronic properties are treated with GGA + U approach, which brings out the important role played by the d-state of noble metal (Cu) and give the correct nature of the energy band gap. Our obtained results show that both compounds exhibit semi-conductor behaviour with direct band gap.

Ab initio study of structural, mechanical, thermal and electronic properties of perovskites Sr(Li,Pd)H3

2016 ◽  
Vol 30 (04) ◽  
pp. 1650003 ◽  
Author(s):  
S. Benlamari ◽  
S. Amara Korba ◽  
S. Lakel ◽  
H. Meradji ◽  
S. Ghemid ◽  
...  
Keyword(s):  
Bulk Modulus ◽  
Electronic Properties ◽  
Elastic Constants ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Local Density ◽  
Velocity Variation ◽  
Full Potential ◽  
Generalized Gradient ◽  
Electronic Band

The structural, elastic, thermal and electronic properties of perovskite hydrides SrLiH3 and SrPdH3 have been investigated using the all-electron full-potential linear augmented plane wave (FP-LAPW) method based on the density functional theory (DFT). For the exchange-correlation potential, local-density approximation (LDA) and generalized gradient approximation (GGA) have been used to calculate theoretical lattice parameters, bulk modulus, and its pressure derivative. The present results are in good agreement with available theoretical and experimental data. The three independent elastic constants [Formula: see text], [Formula: see text] and [Formula: see text] are also reported. From electronic band structure and density of states (DOSs), it is found that SrLiH3 is an insulator characterized by an indirect gap of 3.48 eV, while SrPdH3 is metallic with a calculated DOSs at Fermi energy of 0.745 states/eV-unit cell. Poisson’s ratio [Formula: see text], Young’s modulus (E), shear modulus (G), anisotropy factor (A), average sound velocities [Formula: see text] and density [Formula: see text] of these compounds are also estimated for the first time. The Debye temperature is deduced from the average sound velocity. Variation of elastic constants and bulk modulus of these compounds as a function of pressure is also reported. Pressure and thermal effects on some macroscopic properties are predicted using the quasi-harmonic Debye model.

Effect of Pressure on Structural, Electronic and Elastic Properties of Cubic (Pm3m) SnTiO3 Using First Principle Calculation

2012 ◽  
Vol 501 ◽  
pp. 342-346 ◽  
Author(s):  
M.F.M. Taib ◽  
M.K. Yaakob ◽  
Amreesh Chandra ◽  
Abdul Kariem Mohd Arof ◽  
M.Z.A. Yahya
Keyword(s):  
Band Gap ◽  
Elastic Properties ◽  
Elastic Constants ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Local Density ◽  
Perovskite Oxide ◽  
First Principles Calculation ◽  
Cubic Phase ◽  
Electronic Band

The electronic band structure, density of state and elastic properties of lead-free perovskite oxide SnTiO3 (ST) were investigated by employing first principles calculation using the Density Functional Theory (DFT) within local density approximation (LDA). The energy band gap was calculated from the separation between the Ti 3d (conduction band) and the maximum of O 2p (valence band). This gives an indirect band gap of 2.36 eV. The elastic constants and their pressure dependence were calculated up to 30 GPa and the independent elastic constants (C11, C12, and C44), bulk modules, B were obtained and analyzed. The results showed that SnTiO3 have a mechanical stability in cubic phase (Pm3m).

Electronic Structures of Wide Band-Gap (AlN)m(GaN)n[001] Superlattices

1995 ◽  
Vol 395 ◽  
Author(s):  
Z.-J. Tian ◽  
M.W.C. Dharma-Wardana ◽  
L.J. Lewis
Keyword(s):  
Band Gap ◽  
Electronic Band Structure ◽  
Wide Band ◽  
Orbital Method ◽  
Full Potential ◽  
Wide Band Gap ◽  
Electronic Band ◽  
Level Shifts ◽  
Direct Band ◽  
Near Term

ABSTRACTWide bandgap III-V nitrides, such as GaN and AlN, have become topical in the near-term technology of blue lasers. We report detailed electronic band-structure calculations for (AlN)m(GaN)n [001] zinc-blende superlattices (SL), with m + n ≤ 12, using the all-electron full-potential linear-muffin-tin-orbital method. For n ≥ 3, the SL are found to have a direct band gap. For n ≤ 2 and m ≥ 3, all the band gaps are indirect. In ultrathin SL, m ≤ 3 and n ≤ 2, only (m, n)= (3,1) is found to have an indirect gap. The band offsets are estimated by calculating the core-level shifts of nitrogen atoms in the central planes of the GaN and A1N layers. The calculated densities of states, electron- and hole- effective masses (m), etc., as a function of m and n, are reported; a remarkable dependence of m on the number of layers is revealed.

scholarly journals High Pressure Study of Structural and Electronic Properties of PbSe

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
P. Bhambhani ◽  
K. Kabra ◽  
B. K. Sharma ◽  
G. Sharma
Keyword(s):  
High Pressure ◽  
Electronic Properties ◽  
Energy Gap ◽  
Electronic Band Structure ◽  
Local Density ◽  
Structural Phase ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Structural And Electronic Properties ◽  
Direct Band

High pressure structural phase transition and electronic properties have been investigated using the linear combination of atomic orbitals (LCAO) method with two exchange-correlation approximations, the generalized gradient approximation (GGA) and local density approximation (LDA). The present study shows phase transitions from B1 to B27 and B27 to B2 at 6.24 GPa and 16.39 GPa, respectively. Lattice constant, bulk modulus, and energy gap of pressure-induced PbSe are found to be in good agreement with previous theoretical and experimental results. Variation of electronic band structure with pressure shows direct band gap along L point of the Brillouin zone.

First Principles Study on Structural and Electronic Properties of PZT and PSnZT Using Density Functional Theory

2016 ◽  
Vol 846 ◽  
pp. 734-739 ◽  
Author(s):  
N.H. Hussin ◽  
Mohamad Fariz Mohamad Taib ◽  
F.W. Badrudin ◽  
N.A. Johari ◽  
Nunshaimah Salleh ◽  
...  
Keyword(s):  
Density Functional ◽  
Electronic Band Structure ◽  
Local Density ◽  
Geometry Optimization ◽  
Lone Pair ◽  
Lattice Parameter ◽  
Density Of State ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Indirect Band Gap

The geometry optimization of the tetragonal supercell 1x1x2 (P4mm, 99 space group) of PZT and PSnZT were calculated using different exchange correlation functional such as Local Density Approximate (LDA-CAPZ) and Generalized Gradient Approximation (GGA-PBE & GGA-PBEsol).The calculation using functional GGA-PBEsol exhibits the most accurate values of lattice parameter and volume of structure relative to the experiment results with typical error of approximately 1% underestimate (only for PZT-as reference materials). The electronic band structure and density of state (DOS) were also studied in order to understand the electron density and hybrization between cation and anion in the compound. The density of state studies indicated existing of hybridizations among anion O 2p, cation Pb 6s/Sn 5s (special lone pair) and the Ti 3d/Zr 4d states of PZT and PSnZT compound. An indirect band gap was respectively obtained for both cubic PZT and PSnZT at the F-G and Q-G point with 3.154 eV and 2.571 eV.

Electronic, Thermal, and Superconducting Properties of Metal Nitrides (MN) and Metal Carbides (MC) (M=V, Nb, Ta) Compounds by First Principles Studies

2015 ◽  
Vol 70 (9) ◽  
pp. 721-728
Author(s):  
G. Subhashree ◽  
S. Sankar ◽  
R. Krithiga
Keyword(s):  
Band Structure ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Local Density ◽  
Orbital Method ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
Transition Elements ◽  
Electronic Density ◽  
Electronic Band

AbstractStructural, electronic, and superconducting properties of carbides and nitrides of vanadium (V), niobium (Nb), and tantalum (Ta) (group V transition elements) have been studied by computing their electronic band structure characteristics. The electronic band structure calculations have been carried out based on the density functional theory (DFT) within the local density approximation (LDA) by using the tight binding linear muffin tin orbital method. The NaCl-type cubic structures of MN and MC (M=V, Nb, Ta) compounds have been confirmed from the electronic total energy minimum of these compounds. The ground state properties, such as equilibrium lattice constant (a0), bulk modulus (B), and Wigner–Seitz radius (S0) are determined and compared with available data. The electronic density of states reveals the metallic nature of the chosen materials. The electronic specific heat coefficient, Debye temperature, and superconducting transition temperature obtained from the band structure results are found to agree well with the earlier reported literature.

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