scholarly journals Many-body effects in semiconducting single-wall silicon nanotubes

2014 ◽  
Vol 5 ◽  
pp. 19-25 ◽  
Author(s):  
Wei Wei ◽  
Timo Jacob
Keyword(s):  
Binding Energies ◽  
Band Gaps ◽  
Many Body ◽  
Nanoscale Device ◽  
Strong Electron ◽  
Self Energy ◽  
Silicon Nanotubes ◽  
Particle Level ◽  
The Many ◽  
Silicon Based

The electronic and optical properties of semiconducting silicon nanotubes (SiNTs) are studied by means of the many-body Green’s function method, i.e., GW approximation and Bethe–Salpeter equation. In these studied structures, i.e., (4,4), (6,6) and (10,0) SiNTs, self-energy effects are enhanced giving rise to large quasi-particle (QP) band gaps due to the confinement effect. The strong electron−electron (e−e) correlations broaden the band gaps of the studied SiNTs from 0.65, 0.28 and 0.05 eV at DFT level to 1.9, 1.22 and 0.79 eV at GW level. The Coulomb electron−hole (e−h) interactions significantly modify optical absorption properties obtained at noninteracting-particle level with the formation of bound excitons with considerable binding energies (of the order of 1 eV) assigned: the binding energies of the armchair (4,4), (6,6) and zigzag (10,0) SiNTs are 0.92, 1.1 and 0.6 eV, respectively. Results in this work are useful for understanding the physics and applications in silicon-based nanoscale device components.

scholarly journals Entangling Lattice-Trapped Bosons with a Free Impurity: Impact on Stationary and Dynamical Properties

Entropy ◽  
2021 ◽  
Vol 23 (3) ◽  
pp. 290
Author(s):  
Maxim Pyzh ◽  
Kevin Keiler ◽  
Simeon I. Mistakidis ◽  
Peter Schmelcher
Keyword(s):  
Structural Changes ◽  
Many Body ◽  
Wide Range ◽  
Entropy Measures ◽  
Particle Level ◽  
The Many ◽  
The One ◽  
Tunneling Dynamics ◽  
The Individual ◽  
Trapped Bosons

We address the interplay of few lattice trapped bosons interacting with an impurity atom in a box potential. For the ground state, a classification is performed based on the fidelity allowing to quantify the susceptibility of the composite system to structural changes due to the intercomponent coupling. We analyze the overall response at the many-body level and contrast it to the single-particle level. By inspecting different entropy measures we capture the degree of entanglement and intraspecies correlations for a wide range of intra- and intercomponent interactions and lattice depths. We also spatially resolve the imprint of the entanglement on the one- and two-body density distributions showcasing that it accelerates the phase separation process or acts against spatial localization for repulsive and attractive intercomponent interactions, respectively. The many-body effects on the tunneling dynamics of the individual components, resulting from their counterflow, are also discussed. The tunneling period of the impurity is very sensitive to the value of the impurity-medium coupling due to its effective dressing by the few-body medium. Our work provides implications for engineering localized structures in correlated impurity settings using species selective optical potentials.

scholarly journals Benchmarking Several van der Waals Dispersion Approaches for the Description of Intermolecular Interactions

2018 ◽  
Author(s):  
Julien Claudot ◽  
Won June Kim ◽  
Anant Dixit ◽  
Hyungjun Kim ◽  
Tim Gould ◽  
...  
Keyword(s):  
Van Der Waals ◽  
Chem Phys ◽  
Binding Energies ◽  
Van Der Waals Interactions ◽  
Density Functionals ◽  
Many Body ◽  
Blind Test ◽  
Molecular Systems ◽  
Test Sets ◽  
The Many

Seven methods, including three van der Waals density functionals (vdW-DFs) and four different variants of the Tkatchenko-Scheffler (TS) methods, are tested on the A24, L7, and Taylor <i>et al.</i>'s "blind" test sets. It is found that for these systems, the vdW-DFs perform better that the TS methods. In particular, the vdW-DF-cx functional gives binding energies that are the closest to the reference values, while the many body correction of TS does not always lead to an improvement in the description of molecular systems. In light of these results, several directions for further improvements to describe van der Waals interactions are discussed.<br><br>Published as <i>J. Chem. Phys.</i> <b>148</b>, 064112 (2018)<br>

Study of Unbound HePs Using Exact Diagonalization Technique

2012 ◽  
Vol 733 ◽  
pp. 38-42
Author(s):  
Asier Zubiaga ◽  
Filip Tuomisto ◽  
Martti Puska
Keyword(s):  
Variational Method ◽  
Interaction Potential ◽  
Exact Diagonalization ◽  
Wave Functions ◽  
Many Body ◽  
Strong Electron ◽  
Stochastic Variational Method ◽  
Explicitly Correlated ◽  
Pauli Repulsion ◽  
The Many

The many-body wavefunction of the unbound He-Ps system has been studied by the exact diagonalization of a explicitly correlated gaussians basis optimized by a stochastic variational method. The nucleus-positron distance has been varied by constraining the parameters of the nucleus-positron correlated gaussian term. The constraining technique allows to describe He and Ps interacting at different distances. The calculated wavefunction can be approximated as composed by weakly perturbed He and Ps atoms. The electron forming the Ps tends to be farther from the nucleus than the positron due to the strong electron-electron Pauli repulsion with the electrons of He. The described technique gives accurate energy and wave functions for Ps interacting with atoms that can be used to calculate the interaction potential of Ps with molecular matter.

scholarly journals Many-Electron QED with Redefined Vacuum Approach

Symmetry ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1014
Author(s):  
Romain N. Soguel ◽  
Andrey V. Volotka ◽  
Dmitry A. Glazov ◽  
Stephan Fritzsche
Keyword(s):  
Perturbation Theory ◽  
Electronic Configuration ◽  
Bound State ◽  
Many Body ◽  
Photon Exchange ◽  
Self Energy ◽  
Many Body Perturbation Theory ◽  
Formula Derivation ◽  
The Many ◽  
The One

The redefined vacuum approach, which is frequently employed in the many-body perturbation theory, proved to be a powerful tool for formula derivation. Here, we elaborate this approach within the bound-state QED perturbation theory. In addition to general formulation, we consider the particular example of a single particle (electron or vacancy) excitation with respect to the redefined vacuum. Starting with simple one-electron QED diagrams, we deduce first- and second-order many-electron contributions: screened self-energy, screened vacuum polarization, one-photon exchange, and two-photon exchange. The redefined vacuum approach provides a straightforward and streamlined derivation and facilitates its application to any electronic configuration. Moreover, based on the gauge invariance of the one-electron diagrams, we can identify various gauge-invariant subsets within derived many-electron QED contributions.

scholarly journals Benchmarking Several van der Waals Dispersion Approaches for the Description of Intermolecular Interactions

2018 ◽  
Author(s):  
Julien Claudot ◽  
Won June Kim ◽  
Anant Dixit ◽  
Hyungjun Kim ◽  
Tim Gould ◽  
...  
Keyword(s):  
Intermolecular Interactions ◽  
Van Der Waals ◽  
Binding Energies ◽  
Van Der Waals Interactions ◽  
Density Functionals ◽  
Many Body ◽  
Blind Test ◽  
Molecular Systems ◽  
Test Sets ◽  
The Many

Seven methods, including three van der Waals density functionals (vdW-DFs) and four different variants of the Tkatchenko-Scheffler (TS) methods, are tested on the A24, L7, and Taylor <i>et al.</i>'s "blind" test sets. It is found that for these systems, the vdW-DFs perform better that the TS methods. In particular, the vdW-DF-cx functional gives binding energies that are the closest to the reference values, while the many body correction of TS does not always lead to an improvement in the description of molecular systems. In light of these results, several directions for further improvements to describe van der Waals interactions are discussed.<br>

SELF-ENERGY REVISION OPERATOR THEORY FOR THE MANY-BODY PROBLEM: APPLICATION TO DYNAMICAL PROPERTIES OF THE ELECTRON GAS

2001 ◽  
Vol 15 (19n20) ◽  
pp. 2595-2610 ◽  
Author(s):  
YASUTAMI TAKADA
Keyword(s):  
Density Functional ◽  
Body Problem ◽  
Dynamic Properties ◽  
Electron Gas ◽  
Many Body ◽  
Functional Theory ◽  
Correlation Kernel ◽  
Exchange Correlation ◽  
Self Energy ◽  
The Many

An approximation scheme is proposed for implementing the algorithm to obtain the exact self-energy in the many-body problem [Phys. Rev.B52, 12708 (1995)]. This scheme relates the self-energy revision operator ℱ, the key quantity in the algorithm, with fxc(q,ω) the frequency-dependent exchange-correlation kernel appearing in the time-dependent density functional theory. We illustrate this scheme by applying it to the calculation of dynamic properties of the electron gas at metallic densities.

The Self Energy Approach for Calculation of Quasiparticle Energies in Materials Systems

1988 ◽  
Vol 141 ◽  
Author(s):  
Mark S. Hybertsen
Keyword(s):  
Energy Approach ◽  
The Self ◽  
Electron Interaction ◽  
Many Body ◽  
Self Energy ◽  
Short Period ◽  
Bulk Semiconductors ◽  
Spectroscopic Probes ◽  
Short Period Superlattices ◽  
The Many

AbstractA self energy approach directly taking into account the many-body nature of the electron-electron interaction is described which gives an excellent account of the quasiparticle band energies in semiconductors and insulators. The self energy approach provides a crucial link between structural models and spectroscopic probes of materials systems. Applications to bulk semiconductors, semiconductor surfaces and short period superlattices are described. A model for the screened Coulomb interaction can reduce the amount of computation required. Applicability of bulk self energy results to more complex systems, e.g. surfaces, is discussed.

The description of collective motions in terms of many-body perturbation theory

1957 ◽  
Vol 240 (1223) ◽  
pp. 539-560 ◽  
Keyword(s):  
Collective Motion ◽  
Electron Plasma ◽  
Perturbation Series ◽  
Many Body ◽  
Self Energy ◽  
Collective Motions ◽  
Many Body Perturbation Theory ◽  
Set Up ◽  
The Many ◽  
Diagrammatic Method

In this and a succeeding paper it is shown how a theory equivalent to the Bohm & Pines collective motion theory of the electron plasma can be derived directly from a perturbation series which gives in principle an exact solution of the many-body problem. This result is attained by making use of a diagrammatic method of analysis of the perturbation series. By a process analogous to the elimination of photon self-energy parts from the electrodynamic S matrix it is found possible to simplify the perturbation series, introducing a modified interaction between the particles. A useful integral equation for this modified interaction can be set up, and it is shown how the energy of the system can be expressed in terms of the modified interaction. The close connexion between this approach and the dielectric theory of plasma oscillations is indicated.

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