scholarly journals Electrostatic Interaction of Point Charges in Three-Layer Structures: The Classical Model

2019 ◽  
Vol 4 (2) ◽  
pp. 44 ◽  
Author(s):  
Alexander M. Gabovich ◽  
Alexander I. Voitenko
Keyword(s):  
Electrostatic Interaction ◽  
Classical Model ◽  
Many Body ◽  
Electron Hole ◽  
Analytical Approximations ◽  
Finite Term ◽  
Layer Structures ◽  
Specific Calculations ◽  
The Subject ◽  
Analytical Series

Electrostatic interaction energy W between two point charges in a three-layer plane system was calculated on the basis of the Green’s function method in the classical model of constant dielectric permittivities for all media involved. A regular method for the calculation of W ( Z , Z ′ , R ) , where Z and Z ′ are the charge coordinates normal to the interfaces, and R the lateral (along the interfaces) distance between the charges, was proposed. The method consists in substituting the evaluation of integrals of rapidly oscillating functions over the semi-infinite interval by constructing an analytical series of inverse radical functions to a required accuracy. Simple finite-term analytical approximations of the dependence W ( Z , Z ′ , R ) were proposed. Two especially important particular cases of charge configurations were analyzed in more detail: (i) both charges are in the same medium and Z = Z ′ ; and (ii) the charges are located at different interfaces across the slab. It was demonstrated that the W dependence on the charge–charge distance S = R 2 + Z − Z ′ 2 differs from the classical Coulombic one W ∼ S − 1 . This phenomenon occurs due to the appearance of polarization charges at both interfaces, which ascribes a many-body character to the problem from the outset. The results obtained testify, in particular, that the electron–hole interaction in heterostructures leading to the exciton formation is different in the intra-slab and across-slab charge configurations, which is usually overlooked in specific calculations related to the subject concerned. Our consideration clearly demonstrates the origin, the character, and the consequences of the actual difference. The often used Rytova–Keldysh approximation was analyzed. The cause of its relative success was explained, and the applicability limits were determined.

scholarly journals Exciton-polaron Rydberg states in monolayer MoSe2 and WSe2

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Erfu Liu ◽  
Jeremiah van Baren ◽  
Zhengguang Lu ◽  
Takashi Taniguchi ◽  
Kenji Watanabe ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Excited States ◽  
Ground State ◽  
Transition Metal Dichalcogenides ◽  
Rydberg States ◽  
Energy Shift ◽  
Many Body ◽  
Electron Hole ◽  
Metal Dichalcogenides ◽  
Excitonic States

AbstractExciton polaron is a hypothetical many-body quasiparticle that involves an exciton dressed with a polarized electron-hole cloud in the Fermi sea. It has been evoked to explain the excitonic spectra of charged monolayer transition metal dichalcogenides, but the studies were limited to the ground state. Here we measure the reflection and photoluminescence of monolayer MoSe2 and WSe2 gating devices encapsulated by boron nitride. We observe gate-tunable exciton polarons associated with the 1 s–3 s exciton Rydberg states. The ground and excited exciton polarons exhibit comparable energy redshift (15~30 meV) from their respective bare excitons. The robust excited states contradict the trion picture because the trions are expected to dissociate in the excited states. When the Fermi sea expands, we observe increasingly severe suppression and steep energy shift from low to high exciton-polaron Rydberg states. Their gate-dependent energy shifts go beyond the trion description but match our exciton-polaron theory. Our experiment and theory demonstrate the exciton-polaron nature of both the ground and excited excitonic states in charged monolayer MoSe2 and WSe2.

scholarly journals Quantum many-body effects on Rydberg excitons in cuprous oxide

2021 ◽  
Author(s):  
D. Semkat ◽  
H. Fehske ◽  
H. Stolz
Keyword(s):  
Perturbation Theory ◽  
Oscillator Strength ◽  
Cuprous Oxide ◽  
Many Body ◽  
Electron Hole ◽  
First Order ◽  
Electron Hole Plasma ◽  
Plasma Line ◽  
Many Body Effects ◽  
First Order Perturbation

AbstractWe investigate quantum many-body effects on Rydberg excitons in cuprous oxide induced by the surrounding electron-hole plasma. Line shifts and widths are calculated by full diagonalisation of the plasma Hamiltonian and compared to results in first order perturbation theory, and the oscillator strength of the exciton lines is analysed.

PHASE MODEL REDUCTION AND PHASE LOCKING OF COUPLED NONLINEAR OSCILLATORS

2010 ◽  
Vol 20 (03) ◽  
pp. 645-656 ◽  
Author(s):  
MICHELE BONNIN ◽  
FERNANDO CORINTO ◽  
MARCO GILLI
Keyword(s):  
Applied Sciences ◽  
Phase Locking ◽  
Phase Model ◽  
Phase Variable ◽  
Van Der Pol ◽  
Periodically Driven ◽  
Analytical Approximations ◽  
Coupled Nonlinear Oscillators ◽  
Successful Approach ◽  
The Subject

The synchronization of an oscillator with an external stimulus or between coupled elements is the subject of intense research in many areas of applied sciences. The most successful approach is based on phase modeling, founded on the idea to represent each oscillator by a phase variable. Phase models have been analyzed with a wealth of details and in a plethora of different variants, but little research has been done in view of the reduction of a physical system to the corresponding phase model. In this paper we investigate the possibility, at least within the context of analytical approximations, to obtain the phase model corresponding to a given nonlinear system. Both periodically driven and coupled oscillators are considered, and examples based on Stuart–Landau and van der Pol systems are given.

scholarly journals Dynamic simulations of many-body electrostatic self-assembly

2018 ◽  
Vol 376 (2115) ◽  
pp. 20170143 ◽  
Author(s):  
Eric B. Lindgren ◽  
Benjamin Stamm ◽  
Yvon Maday ◽  
Elena Besley ◽  
A. J. Stace
Keyword(s):  
Self Assembly ◽  
Experimental Studies ◽  
Charged Particles ◽  
Theoretical Chemistry ◽  
Many Body ◽  
Single Particles ◽  
Theme Issue ◽  
Dynamic Simulations ◽  
The Subject ◽  
Small Clusters

Two experimental studies relating to electrostatic self-assembly have been the subject of dynamic computer simulations, where the consequences of changing the charge and the dielectric constant of the materials concerned have been explored. One series of calculations relates to experiments on the assembly of polymer particles that have been subjected to tribocharging and the simulations successfully reproduce many of the observed patterns of behaviour. A second study explores events observed following collisions between single particles and small clusters composed of charged particles derived from a metal oxide composite. As before, observations recorded during the course of the experiments are reproduced by the calculations. One study in particular reveals how particle polarizability can influence the assembly process. This article is part of the theme issue ‘Modern theoretical chemistry’.

The classical model of contract: the product of a revolution in legal thought?

Legal Studies ◽  
2010 ◽  
Vol 30 (4) ◽  
pp. 513-532
Author(s):  
Warren Swain
Keyword(s):  
Eighteenth Century ◽  
Sustained Attention ◽  
Social Factors ◽  
Driving Forces ◽  
Classical Model ◽  
Contract Law ◽  
The Past ◽  
Legal Literature ◽  
The Subject ◽  
Proper Weight

Writing in the introduction to his new treatise on contract in 1826, Joseph Chitty observed that ‘Perhaps no branch of the jurisprudence of this country has of late years been more subject of judicial inquiry and decision than the Law of Contracts’. It is generally accepted that the so-called classical model of contract law, which remains influential into the present day, was created at this time. Ever since the subject first attracted sustained attention from legal historians in the 1970s, the driving forces of these developments have been contested. Some saw legal change as a product of economic and social factors. For others the reception of new ways of thinking and legal literature provided a more convincing explanation. What is not usually disputed is that there was a fundamental revolution in contract doctrine and literature in the nineteenth century. This assumption is open to challenge. It fails to give proper weight to the past. In fact these changes were deeply rooted in the eighteenth century and even earlier.

Quasi‐analytical approximations and series in electromagnetic modeling

Geophysics ◽  
2000 ◽  
Vol 65 (6) ◽  
pp. 1746-1757 ◽  
Author(s):  
Michael S. Zhdanov ◽  
Vladimir I. Dmitriev ◽  
Sheng Fang ◽  
Gábor Hursán
Keyword(s):  
Integral Equation ◽  
Linear Approximation ◽  
Linear Equations ◽  
Integral Equation Method ◽  
Forward Modeling ◽  
Computational Effort ◽  
Correct Result ◽  
Electromagnetic Modeling ◽  
Analytical Approximations ◽  
Analytical Series

The quasi‐linear approximation for electromagnetic forward modeling is based on the assumption that the anomalous electrical field within an inhomogeneous domain is linearly proportional to the background (normal) field through an electrical reflectivity tensor λ⁁. In the original formulation of the quasi‐linear approximation, λ⁁ was determined by solving a minimization problem based on an integral equation for the scattering currents. This approach is much less time‐consuming than the full integral equation method; however, it still requires solution of the corresponding system of linear equations. In this paper, we present a new approach to the approximate solution of the integral equation using λ⁁ through construction of quasi‐analytical expressions for the anomalous electromagnetic field for 3-D and 2-D models. Quasi‐analytical solutions reduce dramatically the computational effort related to forward electromagnetic modeling of inhomogeneous geoelectrical structures. In the last sections of this paper, we extend the quasi‐analytical method using iterations and develop higher order approximations resulting in quasi‐analytical series which provide improved accuracy. Computation of these series is based on repetitive application of the given integral contraction operator, which insures rapid convergence to the correct result. Numerical studies demonstrate that quasi‐analytical series can be treated as a new powerful method of fast but rigorous forward modeling solution.

scholarly journals Electron-hole asymmetric integer and fractional quantum Hall effect in bilayer graphene

Science ◽  
2014 ◽  
Vol 345 (6192) ◽  
pp. 55-57 ◽  
Author(s):  
A. Kou ◽  
B. E. Feldman ◽  
A. J. Levin ◽  
B. I. Halperin ◽  
K. Watanabe ◽  
...  
Keyword(s):  
Hall Effect ◽  
Quantum Hall Effect ◽  
Quantum Hall ◽  
Bilayer Graphene ◽  
Fractional Quantum Hall Effect ◽  
Many Body ◽  
Electron Hole ◽  
Fractional Quantum ◽  
Fractional Quantum Hall ◽  
Lowest Landau Level

The nature of fractional quantum Hall (FQH) states is determined by the interplay between the Coulomb interaction and the symmetries of the system. The distinct combination of spin, valley, and orbital degeneracies in bilayer graphene is predicted to produce an unusual and tunable sequence of FQH states. Here, we present local electronic compressibility measurements of the FQH effect in the lowest Landau level of bilayer graphene. We observe incompressible FQH states at filling factors ν = 2p + 2/3, with hints of additional states appearing at ν = 2p + 3/5, where p = –2, –1, 0, and 1. This sequence breaks particle-hole symmetry and obeys a ν → ν + 2 symmetry, which highlights the importance of the orbital degeneracy for many-body states in bilayer graphene.

scholarly journals Más allá de Piaget: cognición adulta y educación

10.14201/2845 ◽  
2009 ◽  
Vol 11 ◽  
Author(s):  
Antonio Víctor Martín García
Keyword(s):  
Cognitive Development ◽  
Life Span ◽  
Educational Intervention ◽  
Classical Model ◽  
The State ◽  
Information Process ◽  
The Subject ◽  
Pedagogical Theory ◽  
Adult Cognition ◽  
The Way

RESUMEN: El objetivo de este artículo es intentar una aproximación a la descripción del tipo de pensamiento que utilizan los adultos. Partimos de la base en nuestro trabajo de que el conocimiento sobre el modo como piensan las personas adultas se presenta como un aspecto clave para la teoría pedagógica y especialmente para la práctica, cuando se orienta hacia este tipo de alumnos. Para ello, organizamos el texto integrando el concepto de pensamiento en un constructo más amplio y comprensivo como es el de cognición. Desde ese marco realizamos, en primer lugar, una síntesis crítica de la teoría piagetiana en lo referente al desarrollo cognitivo por cuanto representa el modelo, ya clásico, más elaborado sobre el tema, y en segundo, un análisis de algunas de las formulaciones teóricas y empíricas recientes más importantes sobre la cognición adulta, como por ejemplo las derivadas del procesamiento de la información, de la perspectiva del Life-span, o del denominado modelo de encapsulación. Terminamos intentando ofrecer el estado de la cuestión en relación con los aspectos nucleares del pensamiento adulto. Todo ello con vistas a apoyar procesos de intervención e investigación educativa en este campo.ABSTRACT: The aim this article is to attempt an approach to a description of the type of thought that adults use. We take for granted in our paper that knowledge about the way adults think is a key aspect in pedagogical, theory and especially in terms of practice when it is directed towards this type of students. With this in mind we organize the text integrating the concept of thought in a wider an more comprehensive construct which is cognition. From this framework we make, first of all, a critical synthesis of the Piaget theory related to cognitive development in as far as it represents the now classical model, but more developed on the subject and, secondly an analysis of some of the most important of the recent theoretical and empirical formulation of adult cognition, such as those derived from information process and from the Lifespan perspective. We finish attempting to offer the state of the question in relation to nuclear aspects of adult thought. The aim of all this is to support processes of educational intervention and research in this field.

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