scholarly journals On the dynamics of polarons in the strong-coupling limit

2017 ◽  
Vol 29 (10) ◽  
pp. 1750030 ◽  
Author(s):  
Marcel Griesemer
Keyword(s):  
Strong Coupling ◽  
Longitudinal Optical ◽  
Strong Coupling Limit ◽  
Poisson System ◽  
Phonon Modes ◽  
Polar Crystal ◽  
Effective Dynamics ◽  
Optical Modes ◽  
Non Local ◽  
With Memory

The polaron model of H. Fröhlich describes an electron coupled to the quantized longitudinal optical modes of a polar crystal. In the strong-coupling limit, one expects that the phonon modes may be treated classically, which leads to a coupled Schrödinger–Poisson system with memory. For the effective dynamics of the electron, this amounts to a nonlinear and non-local Schrödinger equation. We use the Dirac–Frenkel variational principle to derive the Schrödinger–Poisson system from the Fröhlich model and we present new results on the accuracy of their solutions for describing the motion of Fröhlich polarons in the strong-coupling limit. Our main result extends to [Formula: see text]-polaron systems.

scholarly journals A note on the Fröhlich dynamics in the strong coupling limit

2021 ◽  
Vol 111 (2) ◽  
Author(s):  
David Mitrouskas
Keyword(s):  
Coherent State ◽  
Strong Coupling ◽  
Ground State ◽  
Present Note ◽  
Energy Functional ◽  
Strong Coupling Limit ◽  
Initial State ◽  
Effective Dynamics ◽  
Similar Approximation ◽  
Electron Ground State

AbstractWe revise a previous result about the Fröhlich dynamics in the strong coupling limit obtained in Griesemer (Rev Math Phys 29(10):1750030, 2017). In the latter it was shown that the Fröhlich time evolution applied to the initial state $$\varphi _0 \otimes \xi _\alpha $$ φ 0 ⊗ ξ α , where $$\varphi _0$$ φ 0 is the electron ground state of the Pekar energy functional and $$\xi _\alpha $$ ξ α the associated coherent state of the phonons, can be approximated by a global phase for times small compared to $$\alpha ^2$$ α 2 . In the present note we prove that a similar approximation holds for $$t=O(\alpha ^2)$$ t = O ( α 2 ) if one includes a nontrivial effective dynamics for the phonons that is generated by an operator proportional to $$\alpha ^{-2}$$ α - 2 and quadratic in creation and annihilation operators. Our result implies that the electron ground state remains close to its initial state for times of order $$\alpha ^2$$ α 2 , while the phonon fluctuations around the coherent state $$\xi _\alpha $$ ξ α can be described by a time-dependent Bogoliubov transformation.

Exchange-Correlation Energy Densities and Response Potentials: Connection Between Two Definitions and Analytical Model for the Strong-Coupling Limit of a Stretched Bond

2019 ◽  
Author(s):  
S. Giarrusso ◽  
Paola Gori-Giorgi
Keyword(s):  
Density Functional Theory ◽  
Strong Coupling ◽  
Density Functional ◽  
Correlation Energy ◽  
Order Term ◽  
Strong Coupling Limit ◽  
Local Form ◽  
Coupling Constant ◽  
Functional Theory ◽  
Exchange Correlation

We analyze in depth two widely used definitions (from the theory of conditional probablity amplitudes and from the adiabatic connection formalism) of the exchange-correlation energy density and of the response potential of Kohn-Sham density functional theory. We introduce a local form of the coupling-constant-dependent Hohenberg-Kohn functional, showing that the difference between the two definitions is due to a corresponding local first-order term in the coupling constant, which disappears globally (when integrated over all space), but not locally. We also design an analytic representation for the response potential in the strong-coupling limit of density functional theory for a model single stretched bond.<br>

TOPOLOGY OF THE GRASSMANNIAN σ MODEL ON A LATTICE

1987 ◽  
Vol 02 (08) ◽  
pp. 601-608 ◽  
Author(s):  
T. FUKAI ◽  
M. V. ATRE
Keyword(s):  
Partition Function ◽  
Strong Coupling ◽  
Wilson Loop ◽  
Strong Coupling Limit ◽  
Topological Term

The Grassmannian σ model with a topological term is studied on a lattice. The θ dependence of the partition function and the Wilson loop are evaluated in the strong coupling limit. The latter is shown to be independent of the area at θ = π, as in the CPN−1 model.

scholarly journals Fundamental limitations of the mode temperature concept in strongly coupled systems

2020 ◽  
Vol 75 (8) ◽  
pp. 803-807
Author(s):  
Svend-Age Biehs ◽  
Achim Kittel ◽  
Philippe Ben-Abdallah
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Strong Coupling ◽  
Quantum Systems ◽  
Coupled Systems ◽  
Strong Coupling Limit ◽  
Strongly Coupled ◽  
Fundamental Limitations ◽  
Temperature Concept ◽  
Vacuum Gap

AbstractWe theoretically analyze heat exchange between two quantum systems in interaction with external thermostats. We show that in the strong coupling limit the widely used concept of mode temperatures loses its thermodynamic foundation and therefore cannot be employed to make a valid statement on cooling and heating in such systems; instead, the incorrectly applied concept may result in a severe misinterpretation of the underlying physics. We illustrate these general conclusions by discussing recent experimental results reported on the nanoscale heat transfer through quantum fluctuations between two nanomechanical membranes separated by a vacuum gap.

scholarly journals Approaching the strong coupling limit in single plasmonic nanorods interacting with J-aggregates

2013 ◽  
Vol 3 (1) ◽  
Author(s):  
Gülis Zengin ◽  
Göran Johansson ◽  
Peter Johansson ◽  
Tomasz J. Antosiewicz ◽  
Mikael Käll ◽  
...  
Keyword(s):  
Strong Coupling ◽  
Strong Coupling Limit ◽  
J Aggregates

Long-wavelength lattice vibrations of Ag3In5Se9 and Ag3In5Te9 single crystals — An inversion of LO- and TO-mode frequencies

2016 ◽  
Vol 30 (18) ◽  
pp. 1650229 ◽  
Author(s):  
Nizami Mamed Gasanly
Keyword(s):  
Refractive Index ◽  
Single Crystals ◽  
Longitudinal Optical ◽  
Absorption Index ◽  
Energy Losses ◽  
Optical Parameters ◽  
Lattice Vibrations ◽  
Frequency Range ◽  
Long Wavelength ◽  
Optical Modes

Infrared (IR) reflectivities are registered in the frequency range of 50–2000 cm[Formula: see text] for Ag3In5Se9 and Ag3In5Te9 single crystals grown by Bridgman method. Three infrared-active modes are detected in spectra. The optical parameters, real and imaginary parts of the dielectric function, the function of energy losses, refractive index, absorption index and absorption coefficient were calculated from reflectivity experiments. The frequencies of transverse and longitudinal optical modes (TO and LO modes) and oscillator strength were also determined. The bands detected in infrared spectra were tentatively attributed to various vibration types (valence and valence-deformation). The inversion of LO- and TO-mode frequencies of the sandwiched pair was observed for studied crystals.

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