MECHANICAL AND ELECTRONIC PROPERTIES OF STRAINED LAYER SUPERLATTICES STUDIED BY DENSITY FUNCTIONAL TB AND PATH PROBABILITY METHODS

2002 ◽  
Vol 01 (03n04) ◽  
pp. 357-371 ◽  
Author(s):  
K. MASUDA-JINDO ◽  
R. KIKUCHI
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Statistical Physics ◽  
Tight Binding ◽  
Semiconductor Heterostructures ◽  
Probability Method ◽  
Misfit Dislocations ◽  
Atomic Structures ◽  
Probability Methods ◽  
Interface Disorder

The atomic and electronic structures of semiconductor heterostructures, including steps, misfit dislocations and interface disorder, are studied by using the density-functional tight-binding (TB) method. Atomic structures of misfit dislocations both edge type 1/2 <110> (001) and 60° dislocations in the semiconductor heterostructures, like Si-Ge superlattices and GaAs/Si, InAs/GaAs(001), InP/GaAs(001) systems, are studied by using order of N [O(N)] calculational method. The path probability method (PPM) in the statistical physics is used to study the influence of the interface disorder on the electronic properties of the semiconductor heterostructures. It is shown that the junction relaxation influences quite significantly the electronic and mechanical properties of semiconductor heterostructures. The critical layer thickness hc for the generation of misfit dislocations depends significantly on the interface disorder (increase of hc) at the semiconductor heterostructures.

scholarly journals STRUCTURAL AND ELECTRONIC PROPERTIES OF TRANSITION METAL DI-CHALCOGENIDES (MX2) M=(Mo, W) AND X=(S, Se) IN BULK STATE: A FIRST-PRINCIPLES STUDY

2017 ◽  
Vol 22 (1) ◽  
pp. 41-50
Author(s):  
Ram Prasad Sedhain ◽  
Gopi Chandra Kaphle
Keyword(s):  
Transition Metal ◽  
Electronic Properties ◽  
Density Functional ◽  
Tight Binding ◽  
Calculated Data ◽  
Modern Technology ◽  
Fundamental Aspect ◽  
Bulk State ◽  
Error Bar ◽  
Structural And Electronic Properties

Transition metal di-chalcogenides (MX2) M=(Mo, W) and X=(S, Se) in bulk state are of great interest due to their diverse applications in the field of modern technology as well as to understand the fundamental aspect of Physics. We performed structural and electronic properties of selected systems using density functional theory implemented in Tight Binding Linear Muffin- tin Orbital (TBLMTO) approach with subsequent refinement. The structural optimization is performed through energy minimization process and lattice parameters of optimized structures for MoS2, MoSe2, WS2 and WSe2 are found to be 3.20Å, 3.34Å, 3.27Å and 3.34Å respectively, which are within the error bar less than 5% with experimental values. The band gaps for all TMDCs are found to be of indirect types with semiconducting behaviours. The values of band gap of MoS2, MoSe2, WS2 and WSe2 in bulk state are found to be 1.16eV, 108eV, 1.50eV and 1.29eV respectively which are comparable with experimental and previously calculated data. Due to the symmetric nature of up spin and down spin channels of Density of States (DOS) all the systems selected are found to be non magnetic. However it fully supports the results obtained from band structure calculations. The potential and charge distributions plots support the results. The charge density plots reveals the covalent nature of bond in (100) plane. However (110) plane shows mixed types of bonding.Journal of Institute of Science and TechnologyVolume 22, Issue 1, July 2017, page: 41-50

scholarly journals Hydration Dependent Band Gap Tunability of Self-Assembled Phenylalanine-Tryptophan Nanotubes

2020 ◽  
Author(s):  
Hugo Souza ◽  
Antonio Chaves Neto ◽  
Francisco Sousa ◽  
Rodrigo Amorim ◽  
Alexandre Reily Rocha ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Electronic Properties ◽  
Building Block ◽  
Density Functional ◽  
Tight Binding ◽  
Water Molecules ◽  
Confined Water ◽  
Functional Theory ◽  
Tight Binding Method

In this work, we investigate the effects of building block separation of Phenylalanine-Tryptophan nanotube induced by the confined water molecules on the electronic properties using density-functional theory based tight-binding method. <div><br></div>

scholarly journals Organically interconnected graphene flakes: A flexible 3-D material with tunable electronic bandgap

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
E. Klontzas ◽  
E. Tylianakis ◽  
V. Varshney ◽  
A. K. Roy ◽  
G. E. Froudakis
Keyword(s):  
Chemical Composition ◽  
Band Gap ◽  
Electronic Properties ◽  
Flexible Electronics ◽  
Density Functional ◽  
Organic Molecule ◽  
Tight Binding ◽  
Structural And Electronic Properties ◽  
Graphene Flakes ◽  
Band Gap Tuning

Abstract The structural and electronic properties of molecularly pillared graphene sheets were explored by performing Density Functional based Tight Binding calculations. Several different architectures were generated by varying the density of the pillars, the chemical composition of the organic molecule acting as a pillar and the pillar distribution. Our results show that by changing the pillars density and distribution we can tune the band gap transforming graphene from metallic to semiconducting in a continuous way. In addition, the chemical composition of the pillars affects the band gap in a lesser extent by introducing additional states in the valence or the conduction band and can act as a fine band gap tuning. These unique electronic properties controlled by design, makes Mollecular Pillared Graphene an excellent material for flexible electronics.

scholarly journals A High-Throughput Screening Approach for the Optoelectronic Properties of Conjugated Polymers

2018 ◽  
Author(s):  
Liam Wilbraham ◽  
Enrico Berardo ◽  
Lukas Turcani ◽  
Kim Jelfs ◽  
Martijn Zwijnenburg
Keyword(s):  
Conjugated Polymers ◽  
Electronic Properties ◽  
High Throughput ◽  
High Throughput Screening ◽  
Density Functional ◽  
Tight Binding ◽  
Computational Cost ◽  
Quality Data ◽  
Minor Variation ◽  
Screening Approach

<p>We propose a general high-throughput virtual screening approach for the optical and electronic properties of conjugated polymers. This approach makes use of the recently developed xTB family of low-computational-cost density functional tight-binding methods from Grimme and co-workers, calibrated here to (TD-)DFT data computed for a representative diverse set of (co-)polymers. Parameters drawn from the resulting calibration using a linear model can then be applied to the xTB derived results for new polymers, thus generating near DFT-quality data with orders of magnitude reduction in computational cost. As a result, after an initial computational investment for calibration, this approach can be used to quickly and accurately screen on the order of thousands of polymers for target applications. We also demonstrate that the (opto)electronic properties of the conjugated polymers show only a very minor variation when considering different conformers and that the results of high-throughput screening are therefore expected to be relatively insensitive with respect to the conformer search methodology applied.</p>

Energy stability and electronic properties of carbon nanotorus at a localized breaking of interatomic bonds: computer modeling

2021 ◽  
Author(s):  
O.E. Glukhova ◽  
M.M. Slepchenkov
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Physical Phenomenon ◽  
Tight Binding ◽  
Energy Stability ◽  
The Moment ◽  
20 Nm ◽  
Brenner Potential ◽  
Dynamics Method ◽  
Semiconductor Properties

This paper is devoted to the study of the dynamic processes that occur in the carbon nanotorus during localized breaking of interatomic bonds, and to the analysis of the influence of these processes on the electronic properties of carbon nanotorus. The object of research is a carbon nanotorus with chirality indices (13, 0) with a diameter of 20 nm and a thickness of 1 nm obtained as a result of defect-free folding of a zigzag carbon nanotube of appropriate geometric dimensions into a ring. The behavior of the nanotorus is modeled by the molecular dynamics method using a modified Brenner potential to describe the interaction between atoms. It is shown that over time, the nanotorus straightens into a nanotube, while maintaining energy stability. It is found that the process of nanotorus straightening is accompanied by the appearance of deformation wave-like bends propagating at a speed of 200 m/s along the atomic network of the structure. These bends lead to deformation of the nanotorus and numerous local breaks in the bonds between atoms. However, broken bonds are restored within a few femtoseconds before the structure relaxes in energy, therefore, in general, the atomic framework of the nanotorus remains defect-free after rectification. The results of calculating the distribution of the density of electronic states (DOS) of a nanotorus by the self-consistent charge density functional tight-binding (SCC-DFTB) quantum method showed that at the moment of localized breaking of interatomic bonds around the circumference of the tubular framework, the nanotorus loses its semiconductor properties, becoming a gapless conductor. The discovered physical phenomenon explains the process of nanotorus formation during synthesis accompanied by multiple ruptures of the nanotori and reverse closure of the nanotubes into the nanotori.

Graphyne nanotubes: New Families of Carbon Nanotubes

2002 ◽  
Vol 739 ◽  
Author(s):  
Vitor R. Coluci ◽  
Scheila F. Braga ◽  
Sergio B. Legoas ◽  
Douglas S. Galvão ◽  
Ray H. Baughman
Keyword(s):  
Carbon Nanotubes ◽  
Ab Initio ◽  
Electronic Properties ◽  
Density Functional ◽  
Tight Binding ◽  
Single Walled Nanotubes ◽  
Density Functional Methods ◽  
Functional Methods

ABSTRACTFundamentally new families of carbon single walled nanotubes are proposed. These nanotubes, called graphynes, result from the elongation of covalent interconnections of graphite-based nanotubes by the introduction of yne groups. Similarly to ordinary nanotubes, armchair, zig-zag, and chiral graphyne nanotubes are possible. We present here results for the electronic properties of graphyne based tubes obtained from tight-binding and ab initio density functional methods.

scholarly journals Hydration Dependent Band Gap Tunability of Self-Assembled Phenylalanine-Tryptophan Nanotubes

2020 ◽  
Author(s):  
Hugo Souza ◽  
Antonio Chaves Neto ◽  
Francisco Sousa ◽  
Rodrigo Amorim ◽  
Alexandre Reily Rocha ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Electronic Properties ◽  
Building Block ◽  
Density Functional ◽  
Tight Binding ◽  
Water Molecules ◽  
Confined Water ◽  
Functional Theory ◽  
Tight Binding Method

In this work, we investigate the effects of building block separation of Phenylalanine-Tryptophan nanotube induced by the confined water molecules on the electronic properties using density-functional theory based tight-binding method. <div><br></div>

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