Ab-initio investigation of the influence of chemical compounds on graphene layer properties in fabricated IR detector

2016 ◽  
Author(s):  
L. Ruta ◽  
J. Wozny ◽  
N. Szczecinska ◽  
Z. Lisik
Keyword(s):  
Ab Initio ◽  
Graphene Layer ◽  
Chemical Compounds ◽  
Ir Detector

Ab initio modeling of graphene layer functionalized with boron and nitrogen

2013 ◽  
Author(s):  
Magdalena Woińska ◽  
Karolina Milowska ◽  
Jacek A. Majewski
Keyword(s):  
Ab Initio ◽  
Graphene Layer ◽  
Ab Initio Modeling

scholarly journals The Electronic Structure of Graphene Nanoislands: A CAS-SCF and NEVPT2 Study

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Lucy Cusinato ◽  
Stefano Evangelisti ◽  
Thierry Leininger ◽  
Antonio Monari
Keyword(s):  
Electronic Structure ◽  
Ab Initio ◽  
Graphene Layer ◽  
Tight Binding ◽  
High Symmetry ◽  
Ab Initio Study ◽  
Convex Polygons ◽  
Open Shells ◽  
Regular Convex ◽  
Closed Shells

This paper presents a tight binding and ab initio study of finite graphene nanostructures. The attention is focused on three types of regular convex polygons: triangles, rhombuses, and hexagons, which are the most simple high-symmetry convex structures that can be ideally cut out of a graphene layer. Three different behaviors are evidenced for these three classes of compounds: closed-shells for hexagons; low-spin open-shells for rhombuses; high-spin open-shells for triangles.

scholarly journals Электронная структура графена на карбиде кремния, интеркалированного атомами кремния и кобальта

2021 ◽  
Vol 63 (6) ◽  
pp. 706
Author(s):  
С.М. Дунаевский ◽  
Е.Ю. Лобанова ◽  
Е.К. Михайленко ◽  
И.И. Пронин
Keyword(s):  
Silicon Carbide ◽  
Band Structure ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Buffer Layer ◽  
Graphene Layer ◽  
Cobalt Silicide ◽  
Strongly Coupled ◽  
Spin Polarized ◽  
Cobalt Layer

The results of ab initio calculations of the spin-polarized band structure of graphene on silicon carbide intercalated with cobalt and silicon atoms are presented. It is shown that metal and silicon atoms during intercalation are localized between the substrate and the buffer layer of carbon atoms. Initially, the cobalt layer is strongly coupled with the buffer layer. The subsequent intercalation of silicon and the formation of cobalt silicide leads to a transition from hybridized state to the formation of quasi-freestanding bilayer graphene on the surface of the system due to the transformation of the buffer layer to the second graphene layer.

scholarly journals Применение эмпирических потенциалов для расчета упругих свойств графена

2019 ◽  
Vol 45 (3) ◽  
pp. 52
Author(s):  
А.С. Минкин ◽  
И.В. Лебедева ◽  
А.М. Попов ◽  
А.А. Книжник
Keyword(s):  
Experimental Data ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Elastic Properties ◽  
Poisson’S Ratio ◽  
Graphene Layer ◽  
Poisson's Ratio ◽  
Account System ◽  
Potential Parameters ◽  
Mechanical Phenomena

AbstractThe elastic properties of a flat graphene layer calculated using the classical empirical Tersoff, Brenner, AIREBO, PPBE-G, and LCBOP potentials have been compared. It is shown that, although the popular Brenner and AIREBO potentials have been developed formally taking into account the elastic properties of graphene, they give significant discrepancies in the values of Young’s modulus and Poisson’s ratio. Among the potentials under consideration, the LCBOP potential yields the values of these parameters that are closest to experimental data and results of ab initio calculations in the limit of zero elongation. For the quantitative simulation of mechanical phenomena in graphene-based systems, the potential parameters should be fitted to reproduce elastic properties of graphene completely taking into account system deformations and dependences of these constants on the elongation.

Cytochemical analysis of mast cell granules after poly-dl-lysine action

1978 ◽  
Vol 36 (2) ◽  
pp. 278-279
Author(s):  
R. Courtoy ◽  
L.J. Simar ◽  
J. Christophe
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Chemical Compounds ◽  
Cellular Membrane ◽  
Thin Sections ◽  
Organic Bases ◽  
Ferric Thiocyanate ◽  
Cytochemical Analysis ◽  
Mast Cell Granule ◽  
Amine Liberation

Several chemical compounds induce amine liberation from mast cells but do not necessarily provoque the granule expulsion. For example, poly-dl-lysine induces modifications of the cellular membrane permeability which promotes ion exchange at the level of mast cell granules. Few of them are expulsed but the majority remains in the cytoplasm and appears less dense to the electrons. A cytochemical analysis has been performed to determine the composition of these granules after the polylysine action.We have previously reported that it was possible to demonstrate polyanions on epon thin sections using a cetylpyridinium ferric thiocyanate method. Organic bases are selectively stained with cobalt thiocyanate and the sulfhydryle groups are characterized with a silver methenamine reaction. These techniques permit to reveal the mast cell granule constituents, i.e. heparin, biogenic amines and basic proteins.

Growth of near noble metal Pd and Pt thin film silicides morphology and structure

1984 ◽  
Vol 42 ◽  
pp. 498-499
Author(s):  
E. I. Alessandrini ◽  
M. O. Aboelfotoh
Keyword(s):  
Noble Metals ◽  
Annealing Temperature ◽  
Chemical Compounds ◽  
Barrier Properties ◽  
Solid State Reactions ◽  
Transmission Electron ◽  
Stable Chemical ◽  
Metal Thickness ◽  
Amorphous Si ◽  
Si Films

Considerable interest has been generated in solid state reactions between thin films of near noble metals and silicon. These metals deposited on Si form numerous stable chemical compounds at low temperatures and have found applications as Schottky barrier contacts to silicon in VLSI devices. Since the very first phase that nucleates in contact with Si determines the barrier properties, the purpose of our study was to investigate the silicide formation of the near noble metals, Pd and Pt, at very thin thickness of the metal films on amorphous silicon.Films of Pd and Pt in the thickness range of 0.5nm to 20nm were made by room temperature evaporation on 40nm thick amorphous Si films, which were first deposited on 30nm thick amorphous Si3N4 membranes in a window configuration. The deposition rate was 0.1 to 0.5nm/sec and the pressure during deposition was 3 x 10 -7 Torr. The samples were annealed at temperatures in the range from 200° to 650°C in a furnace with helium purified by hot (950°C) Ti particles. Transmission electron microscopy and diffraction techniques were used to evaluate changes in structure and morphology of the phases formed as a function of metal thickness and annealing temperature.

Ab initio band theory approach to electron energy loss near edge structures

1988 ◽  
Vol 46 ◽  
pp. 506-507
Author(s):  
Xudong Weng ◽  
O.F. Sankey ◽  
Peter Rez
Keyword(s):  
Ab Initio ◽  
Local Density ◽  
Interpolation Method ◽  
Atomic Orbital ◽  
Plane Waves ◽  
Large Set ◽  
Theory Approach ◽  
Band Theory ◽  
Atomic Orbitals ◽  
Pseudopotential Calculations

Single electron band structure techniques have been applied successfully to the interpretation of the near edge structures of metals and other materials. Among various band theories, the linear combination of atomic orbital (LCAO) method is especially simple and interpretable. The commonly used empirical LCAO method is mainly an interpolation method, where the energies and wave functions of atomic orbitals are adjusted in order to fit experimental or more accurately determined electron states. To achieve better accuracy, the size of calculation has to be expanded, for example, to include excited states and more-distant-neighboring atoms. This tends to sacrifice the simplicity and interpretability of the method.In this paper. we adopt an ab initio scheme which incorporates the conceptual advantage of the LCAO method with the accuracy of ab initio pseudopotential calculations. The so called pscudo-atomic-orbitals (PAO's), computed from a free atom within the local-density approximation and the pseudopotential approximation, are used as the basis of expansion, replacing the usually very large set of plane waves in the conventional pseudopotential method. These PAO's however, do not consist of a rigorously complete set of orthonormal states.

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