Cyclacenes and short zigzag nanotubes with alternanting Ge―C bonds: theoretical impacts of Ge on the ground state, strain, and band gap

2014 ◽  
Vol 27 (9) ◽  
pp. 735-746 ◽  
Author(s):  
Maryam Koohi ◽  
Monireh Ghavami ◽  
Bibi Narjes Haerizade ◽  
Hasan Zandi ◽  
Mohammad Zaman Kassaee
Keyword(s):  
Band Gap ◽  
Ground State ◽  
Zigzag Nanotubes

scholarly journals Ground State Properties of the Wide Band Gap Semiconductor Beryllium Sulfide (BeS)

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6128
Author(s):  
Blaise A. Ayirizia ◽  
Janee’ S. Brumfield ◽  
Yuriy Malozovsky ◽  
Diola Bagayoko
Keyword(s):  
Band Gap ◽  
Lattice Constant ◽  
Ground State ◽  
Density Functional ◽  
Local Density ◽  
Wide Band ◽  
Electronic Energy ◽  
Computational Method ◽  
Energy Bands ◽  
Ground State Properties

We report the results from self-consistent calculations of electronic, transport, and bulk properties of beryllium sulfide (BeS) in the zinc-blende phase, and employed an ab-initio local density approximation (LDA) potential and the linear combination of atomic orbitals (LCAO). We obtained the ground state properties of zb-BeS with the Bagayoko, Zhao, and Williams (BZW) computational method, as enhanced by Ekuma and Franklin (BZW-EF). Our findings include the electronic energy bands, the total (DOS) and partial (pDOS) densities of states, electron and hole effective masses, the equilibrium lattice constant, and the bulk modulus. The calculated band structure clearly shows that zb-BeS has an indirect energy band gap of 5.436 eV, from Γ to a point between Γ and X, for an experimental lattice constant of 4.863 Å. This is in excellent agreement with the experiment, unlike the findings of more than 15 previous density functional theory (DFT) calculations that did not perform the generalized minimization of the energy functional, required by the second DFT theorem, which is inherent to the implementation of our BZW-EF method.

Er-Related Emission In Impurities (Nitrogen, Oxygen) Implanted Al0.7Ga0.3As

1997 ◽  
Vol 484 ◽  
Author(s):  
S. Uekusa ◽  
M. Wakutani ◽  
M. Saito ◽  
M. Kumagai
Keyword(s):  
Excited State ◽  
Band Gap ◽  
Ground State ◽  
Thermal Quenching ◽  
Trap Level ◽  
Pl Intensity ◽  
Complex Center

AbstractErbium (Er) was co-implanted with ( i ) nitrogen (N), ( ii) oxygen (0) and (iii) N and 0 into Al0.7Ga0.3As substrates. Compared with the Al0.7Ga0.3As:Er sample, the 20 K Er3+ -related 1.54 μm integrated photoluminescence (PL) intensity from the Al0 7Ga0.3As:Er,N and Al0.7Ga0.3As:Er,N,O samples were enhanced approximately fifteen and ten times more, respectively. Thermal quenching of Er3+-related emission from Al0.7Ga0.3As:Er,N,O was smaller than that of Er3+-related emission from Al0.7.Ga0.3As-Er,N The 20 K Er3+-related 0.98 μm PL which was radiated by transition from the second excited state (4I1/2) to the ground state (4I1/2) was observed. The 0.98 μm PL intensity from Al0.7Ga0.3As:Er,N,O generally decreased with increasing 0 dosage from 1 × 1013 cm−2 to 1 × 1015 cm−2. These results suggest the formation of different complexes composed of Er and the impurities (N,O). This leads to the generation of complex related traps in the band-gap of Al0.7Ga0.3As as a result of the co-implantation of the impurities. It was found that the trap level of the Er-N complex center lay between 2.05 eV and 1.26 eV, and that of the Er-N-O complex center lay between 1.26 eV and 0.82 eV.

Electronic Structure and Ground State Properties of A4[Ag4O4] (A=Na, K and Rb): A First-Principles Study

2013 ◽  
Vol 665 ◽  
pp. 43-48
Author(s):  
Rajagopalan Umamaheswari ◽  
M. Yogeswari ◽  
G. Kalpana
Keyword(s):  
Electronic Structure ◽  
Band Gap ◽  
Ground State ◽  
First Principles ◽  
Density Functional ◽  
Electronic Band Structure ◽  
First Principles Calculation ◽  
Partial Density ◽  
Electronic Band ◽  
Ground State Properties

The first-principles calculation within density functional theory is used to study in detail the electronic structure and ground state properties of alkali-metal oxoargenates A4[Ag4O4] (A= Na, K and Rb). The total energies calculated within the atomic sphere approximation (ASA) were used to determine the ground state properties such as equilibrium lattice parameter, c/a ratio, bulk modulus and cohesive energy. The theoretically calculated equilibrium lattice constants values are in well agreement with the available experimental values. The electronic band structures, total and partial density of states are calculated. The result of electronic band structure shows that the KAgO and RbAgO are direct band gap semiconductors with their gap lying between the Γ-Γ points, whereas NaAgO is found to be an indirect band gap semiconductor with its gap lying between Z-Γ points.

Optical Identification of Mo Related Deep Level Defect in 4H and 6H SiC

2009 ◽  
Vol 615-617 ◽  
pp. 405-408 ◽  
Author(s):  
Andreas Gällström ◽  
Björn Magnusson ◽  
Erik Janzén
Keyword(s):  
Magnetic Resonance ◽  
Band Gap ◽  
Ground State ◽  
Deep Level ◽  
Electronic Configuration ◽  
Electron Structure ◽  
Main Peak ◽  
Optical Identification ◽  
Deep Level Defect ◽  
The Difference

The photoluminescence (PL) from the I 1 centre is observed in p-, n-type as well as in compensated samples, using above band gap excitation. The PL from I 1 in the two polytypes 4H and 6H is very similar, the difference being the position of the main peak, in 4H 1.1521 eV and 1.1057 eV in 6H. We here suggest I-1 to be Mo related based on intentional doping, SIMS results and comparison with earlier reports of Mo in SiC using magnetic resonance techniques. From PL measurements, we analyze the electron structure of the defect, and suggest it be the neutral Mo (4d2) residing on a Si site, the luminescence coming from the transition between the 3A2 multiplet of the first excited electronic configuration and the ground state 3A2.

First principles investigation on the band gap of the ground state of

2010 ◽  
Vol 150 (41-42) ◽  
pp. 1983-1986 ◽  
Author(s):  
Chun-Lan Ma ◽  
Jun Cang
Keyword(s):  
Band Gap ◽  
Ground State ◽  
First Principles

scholarly journals Band Gap Reduction in Ferroelectric BaTiO3 Through Heterovalent Cu-Te Co-Doping for Visible-Light Photocatalysis

2021 ◽  
Vol 9 ◽  
Author(s):  
Rohit Kumar Rohj ◽  
Akmal Hossain ◽  
Priya Mahadevan ◽  
D. D. Sarma
Keyword(s):  
Band Gap ◽  
Ground State ◽  
Density Functional ◽  
Dopant Concentration ◽  
Ferroelectric Properties ◽  
Solar Spectrum ◽  
Visible Light Photocatalysis ◽  
Functional Theory ◽  
Co Doping ◽  
Photovoltaic Materials

It is believed that ferroelectrics may serve as efficient photocatalysts as well as photovoltaic materials but for their large bandgaps which does not allow them to absorb a large part of the solar spectrum. We have explored theoretically within ab-initio density functional theory-based calculations, the efficacy of Cu and Te to co-dope BaTiO3 in reducing its bandgap while retaining its ferroelectric properties. Examining a dopant concentration of 11%, we find an insulating ground state being realized with a band gap reduction of 0.42 eV from the value for undoped BaTiO3 for some doping configurations. Ferroelectric distortions are found to survive even in the presence of doping suggesting possible applications in photocatalysis as well as photovoltaics.

Racah Materials: Role of Atomic Multiplets and Intermediate Valence in f-Electron Systems

MRS Advances ◽  
2016 ◽  
Vol 1 (44) ◽  
pp. 2967-2974 ◽  
Author(s):  
A. I. Lichtenstein ◽  
J. Kolorenc ◽  
A. B. Shick ◽  
M. I. Katsnelson
Keyword(s):  
Electronic Structure ◽  
Band Gap ◽  
Ground State ◽  
Density Functional ◽  
Singlet Ground State ◽  
Intermediate Valence ◽  
Kondo Insulator ◽  
The Density Functional Theory ◽  
Indirect Band Gap ◽  
The Moment

ABSTRACT The electronic structure of PuB6, an actinide analog of SmB6 , was investigated making use of a combination of the density functional theory (DFT), and the exact diagonalization (ED) of an effective discrete Anderson impurity model. Intermediate valence ground state with the f-shell occupation n4f =5.5 for the Pu atom in PuB6 is calculated. The 5f-shell magnetic moment is completely compensated by the moment carried by the electrons in the conduction band. Already in DFT, PuB6 is an insulator with a small amount of holes near the X-point, and the indirect band gap of ≈60 meV. This band gap becomes direct in DFT+ED calculations supporting the idea of “topological Kondo insulator” in PuB6. Connection between the electronic structure of PuB6 and δ-Pu is established. We propose that these materials belong to a new class of intermediate valence “Racah” materials with the multi-orbital “Kondo-like” singlet ground-state.

LINEAR ACENES LINKED THIOPHENE, ELECTRONIC AND CHEMICAL PROPERTIES: PROSPECTS FOR MOLECULAR ORGANIC ELECTRONIC MATERIAL

2016 ◽  
Vol 78 (6-11) ◽  
Author(s):  
A. Musa ◽  
M. A. Saeed ◽  
A. Shaari ◽  
Riadh Sahnoun ◽  
M. Lawal ◽  
...  
Keyword(s):  
Electronic Material ◽  
Band Gap ◽  
Ground State ◽  
State Energy ◽  
Chemical Properties ◽  
Band Gap Energy ◽  
Basis Set ◽  
Exchange Level ◽  
Good Agreement ◽  
And Chemical Properties

We report a theoretical study of linear acene (n=1 to 7) linked thiophene properties functionality. The total ground state and band gap energies, Coulomb potential and nuclear repulsion energy are calculated by DFT, MP2 at B3LYP exchange level of the theory and 6-311G* basis set. The results are in good agreement with the experimental and theoretical values. It is found that the total ground state energy of the system and band gap energy decreases with an increasing number of electrons in the rings. The addition of thiophene molecules tends to improve the electronic and chemical properties of the linear acenes, the material exhibit potential application in the organic molecular electronic material.

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