The misconception in graphene’s dispersion energy simulations

This study aims to find equations and simulations that satisfy the characteristics of graphene’s energy dispersion and identify misconceptions that may occur. Here we give students nine articles about graphene’s dispersion energy. They were asked to identify the equations, parameters, and software used in each of the articles. The assignment was then to make the distribution of the data in a spreadsheet. The parameters used were the lattice constant of 2.46 Å, the range of the k wave function for the x and y axes of -2πa to 2πa, and the interval for each range of 0.1. Each equation is divided into two parts, E(+) and E(-). The analysis was carried out by making a slice in the middle of the x and y axes, as well as the main and off-diagonals. Graphene has Dirac points where the band gap is zero. This means that there is no distance or very small distance between the valence and conduction bands. From this activity, it can be concluded that Rozhkov (2016) has the equations and simulations that best satisfy graphene’s dispersion energy. Misconceptions occur in almost all existing equations and simulations.

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First Principle Investigation of Electronic, Transport, and Bulk Properties of Zinc-Blende Magnesium Sulfide

Electronics ◽

10.3390/electronics9111791 ◽

2020 ◽

Vol 9 (11) ◽

pp. 1791

Author(s):

Uttam Bhandari ◽

Blaise Awola Ayirizia ◽

Yuriy Malozovsky ◽

Lashounda Franklin ◽

Diola Bagayoko

Keyword(s):

Band Gap ◽

Lattice Constant ◽

Density Functional ◽

Local Density ◽

Computational Method ◽

Physical Content ◽

Conduction Bands ◽

Zinc Blende ◽

Densities Of States ◽

Magnesium Sulfide

We have studied electronic, structural, and transport properties of zinc-blende magnesium sulfide (zb-MgS). We employed a local density approximation (LDA) potential and the linear combination of atomic orbitals (LCAO) method. Our computational method is able to reach the ground state of a material, as dictated by the second theorem of density functional theory (DFT). Consequently, our findings have the physical content of DFT and agree with available, corresponding experimental ones. The calculated band gap of zb-MgS, a direct gap equal to 4.43 eV, obtained at the experimental lattice constant of 5.620 Å, completely agrees with the experimental band gap of 4.45 ± 0.2 eV. We also report total (DOS) and partial (pDOS) densities of states, electron and hole effective masses, the equilibrium lattice constant, and the bulk modulus. The calculated pDOS also agree with the experiment for the description of the states at the top and the bottom of the valence and conduction bands, respectively.

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Characteristics of Poly(vinyl Alcohol) (PVA) Based Composites Integrated with Green Synthesized Al3+-Metal Complex: Structural, Optical, and Localized Density of State Analysis

Polymers ◽

10.3390/polym13081316 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1316

Author(s):

Shujahadeen B. Aziz ◽

Muaffaq M. Nofal ◽

Hewa O. Ghareeb ◽

Elham M. A. Dannoun ◽

Sarkawt A. Hussen ◽

...

Keyword(s):

Dielectric Constant ◽

Refractive Index ◽

Metal Complex ◽

Band Gap ◽

Optical Band Gap ◽

Complex Dielectric Constant ◽

Poly Vinyl Alcohol ◽

Optical Parameters ◽

Dispersion Energy ◽

Casting Technique

The influence of dispersing Al-metal complex on the optical properties of PVA was investigated using UV–visible spectroscopy. Polymer composite films with various Al3+-complex amounts in the PVA matrix were arranged by solution casting technique by means of distilled water as a widespread solvent. The formation of Al3+-metal complex was verified through Ultraviolet–visible (UV-Vis) and Fourier-transform infrared spectroscopy (FTIR) examinations. The addition of Al-complex into the polymer matrix led to the recovery of the optical parameters such as dielectric constant (εr and εi) and refractive index (n). The variations of real and imaginary parts of complex dielectric constant as a function of photon wavelength were studied to calculate localized charge density values (N/m*), high-frequency dielectric constant, relaxation time, optical mobility, optical resistivity, and plasma angular frequency (ωp) of electrons. In proportion with Al3+-complex content, the N/m* values were amplified from 3.68 × 1055 kg−1 m−3 to 109 × 1055 kg−1 m−3. The study of optical parameters may find applications within optical instrument manufacturing. The optical band gap was determined from Tauc’s equation, and the type of electronic transition was specified. A remarkable drop in the optical band gap was observed. The dispersion of static refractive index (no) of the prepared composites was analyzed using the theoretical Wemple–DiDomenico single oscillator model. The average oscillator energy (Eo) and oscillator dispersion energy (Ed) parameters were estimated.

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Lattice-constant and band-gap tuning in wurtzite and zincblende BInGaN alloys

Journal of Applied Physics ◽

10.1063/1.5108731 ◽

2019 ◽

Vol 126 (5) ◽

pp. 055702 ◽

Cited By ~ 2

Author(s):

Kevin Greenman ◽

Logan Williams ◽

Emmanouil Kioupakis

Keyword(s):

Band Gap ◽

Lattice Constant ◽

Band Gap Tuning

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Characterizations of Zinc Oxynitride Powders Prepared Under Ammonia Gas Flow

International Journal of Modern Physics B ◽

10.1142/s0217979203019265 ◽

2003 ◽

Vol 17 (08n09) ◽

pp. 1523-1526 ◽

Cited By ~ 2

Author(s):

Takashi Sakamoto ◽

Ryoji Saki ◽

Toshihiro Moriga ◽

Kei Ichiro Murai ◽

Ichiro Nakabayashi

Keyword(s):

Band Gap ◽

Oxygen Content ◽

Lattice Constant ◽

Gas Flow ◽

Optical Band Gap ◽

Zinc Powder ◽

Ammonia Gas

The anti-bixbyite-type zinc oxynitrides Zn 3( N1-xOx ) 2-y could be prepared by directly nitriding zinc powder under ammonia gas flow. Oxygen content x and amount of anion deficiency y decreased with increasing nitriding period at [Formula: see text]. Zn 3( N0.91O0.09 )1.98 could be obtained after the 168 hours of nitridation at [Formula: see text]. Reduction of both x and y, especially x, enhanced the lattice constant and reduced optical band gap of the oxynitride.

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E0 band‐gap energy and lattice constant of ternary Zn1−xMgxSe as functions of composition

Applied Physics Letters ◽

10.1063/1.118132 ◽

1996 ◽

Vol 69 (1) ◽

pp. 97-99 ◽

Cited By ~ 168

Author(s):

B. Jobst ◽

D. Hommel ◽

U. Lunz ◽

T. Gerhard ◽

G. Landwehr

Keyword(s):

Band Gap ◽

Lattice Constant ◽

Band Gap Energy ◽

Gap Energy

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Calculation of dispersion interactions with the geminal-based ring Coupled Cluster Doubles method

Theoretical Chemistry Accounts ◽

10.1007/s00214-020-02657-1 ◽

2020 ◽

Vol 139 (9) ◽

Author(s):

Á. Margócsy ◽

Á. Szabados

Keyword(s):

Wave Function ◽

Asymptotic Behaviour ◽

Noble Gas ◽

Valence Bond ◽

Coupled Cluster ◽

Leading Order ◽

Dispersion Interactions ◽

Dispersion Energy ◽

Generalized Valence Bond ◽

Noble Gas Dimers

Abstract The performance of the recently developed multi-reference extension of ring coupled cluster doubles is investigated for dispersion energy calculations, applied to the generalized valence bond wave function. The leading-order contribution to the dispersion energy is shown to have the correct asymptotic behaviour. Illustrative calculations on noble gas dimers are presented.

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Effect of Sn Incorporation on Physical Parameters of Sb-Se Glassy System

Journal of Scientific Research ◽

10.3329/jsr.v12i4.46048 ◽

2020 ◽

Vol 12 (4) ◽

pp. 545-554

Author(s):

R. Khajuria ◽

A. Sharma ◽

P. Sharma

Keyword(s):

Glass Transition ◽

Transition Temperature ◽

Glass Transition Temperature ◽

Band Gap ◽

Bond Energy ◽

Chalcogenide Glasses ◽

Lone Pair ◽

Physical Parameters ◽

Glassy System ◽

Almost All

The rationale of this study is to investigate band gap tailoring of Sb-Se-Sn chalcogenide glasses. This study has been accompanied by the assessment of various theoretical parameters such as average co-ordination number, Lone-pair of electrons, number of constraints, average heat of atomization, mean bond energy and glass transition temperature. It has been observed that almost all these physical parameters have been enhanced with the increase in tin (Sn) content except Lone-pair of electrons. The number of lone-pair electrons has been decreased with the increase in Sn content. The glass transition temperature has been observed to increase due to the addition of Sn atom in the Se-Sb glassy system. The band gap is decreasing with increase in Sn content due to overall decrease in the average single bond energy of the Sb-Se-Sn glassy system.

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ACOUSTIC BAND GAP FORMATION IN METAMATERIALS

International Journal of Modern Physics B ◽

10.1142/s0217979210057110 ◽

2010 ◽

Vol 24 (25n26) ◽

pp. 4935-4945 ◽

Cited By ~ 2

Author(s):

D. P. ELFORD ◽

L. CHALMERS ◽

F. KUSMARTSEV ◽

G. M. SWALLOWE

Keyword(s):

Band Gap ◽

Lattice Constant ◽

Low Frequency ◽

Band Gaps ◽

Gap Formation ◽

Individual Band ◽

Resonance Band ◽

Frequency Regime ◽

Sonic Crystal ◽

The Individual

We present several new classes of metamaterials and/or locally resonant sonic crystal that are comprised of complex resonators. The proposed systems consist of multiple resonating inclusion that correspond to different excitation frequencies. This causes the formation of multiple overlapped resonance band gaps. We demonstrate theoretically and experimentally that the individual band gaps achieved, span a far greater range (≈ 2kHz) than previously reported cases. The position and width of the band gap is independent of the crystal's lattice constant and forms in the low frequency regime significantly below the conventional Bragg band gap. The broad envelope of individual resonance band gaps is attractive for sound proofing applications and furthermore the devices can be tailored to attenuate lower or higher frequency ranges, i.e., from seismic to ultrasonic.

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First-principles study on electronic, optic, elastic, dynamic and thermodynamic properties of RbH compound

International Journal for Simulation and Multidisciplinary Design Optimization ◽

10.1051/smdo/2015006 ◽

2015 ◽

Vol 6 ◽

pp. A6 ◽

Cited By ~ 5

Author(s):

Sinem Erden Gulebaglan ◽

Emel Kilit Dogan ◽

Mehmet Nurullah Secuk ◽

Murat Aycibin ◽

Bahattin Erdinc ◽

...

Keyword(s):

Thermodynamic Properties ◽

Band Gap ◽

Lattice Constant ◽

First Principles ◽

Density Functional ◽

Temperature Dependent ◽

Functional Theory ◽

Salt Structure ◽

Elastic Lattice ◽

Good Agreement

We performed first-principles calculations to obtain the electronic, optical, elastic, lattice-dynamical and thermodynamic properties of RbH compound with rock salt structure. The ground-state properties, i.e., the lattice constant and the band gap were investigated using a plane wave pseudopotential method within density functional theory. The calculated lattice constant, bulk modulus, energy band gap and elastic constants are reported and compared with previous theoretical and experimental results. Our calculated results and the previous results which are obtained from literature are in a good agreement. Moreover, real and imaginary parts of complex dielectric function, reflectivity spectrum, absorption, extinction coefficient and loss function as a function of photon energy and refractive index with respect to photon wavelength were calculated. In addition, temperature dependent thermodynamic properties such as Helmholtz free energy, internal energy, entropy and specific heat have been studied.

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Electronic Structure of Defects in SnTe

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.701.125 ◽

2013 ◽

Vol 701 ◽

pp. 125-130

Author(s):

Salameh Ahmad

Keyword(s):

Electronic Structure ◽

Band Gap ◽

Valence Band ◽

Fundamental Difference ◽

Density Of State ◽

Defect States ◽

Deep Defect ◽

Conduction Bands ◽

Resonant States ◽

Structure Calculations

Myab initioelectronic structure calculations inRSn2n-1Te2n, n=16, R = a vacancy, Cd, and In show that when Sn atom is substituted by R, the Density of State (DOS) of the valence and conduction bands get strongly perturbed. There are significant changes near the band gap region. Sn vacancy causes very little change near the bottom of the conduction band DOS whereas there is an increase in the DOS near the top of the valence band. Results for In impurity shows that, unlike PbTe, the deep defect states in SnTe are resonant states near the top of the valence band. In PbTe these deep defect states lie in the band-gap region (act asn-type). This fundamental difference in the position of the deep defect states in SnTe and PbTe explains the experimental anomalies seen in the case of In impurities (act asn-type in PbTe andp-type in SnTe).

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