Polaron Formation in a Model Hamiltonian with Covalent Electron–Phonon Interactions

2005 ◽  
Vol 18 (5-6) ◽  
pp. 723-726
Author(s):  
J. Miranda Mena ◽  
J. Mustre de León ◽  
A. R. Bishop
Keyword(s):  
Model Hamiltonian ◽  
Polaron Formation

Light front field theory: An advanced Primer

2007 ◽  
Vol 57 (3) ◽  
Author(s):  
L'ubomír Martinovič
Keyword(s):  
Field Theory ◽  
Detailed Comparison ◽  
Light Front ◽  
Two Dimensional ◽  
Schwinger Model ◽  
Initial Space ◽  
Model Hamiltonian ◽  
Spatial Volume ◽  
Hamiltonian Perturbation Theory ◽  
Light Front Quantization

Light front field theory: An advanced PrimerWe present an elementary introduction to quantum field theory formulated in terms of Dirac's light front variables. In addition to general principles and methods, a few more specific topics and approaches based on the author's work will be discussed. Most of the discussion deals with massive two-dimensional models formulated in a finite spatial volume starting with a detailed comparison between quantization of massive free fields in the usual field theory and the light front (LF) quantization. We discuss basic properties such as relativistic invariance and causality. After the LF treatment of the soluble Federbush model, a LF approach to spontaneous symmetry breaking is explained and a simple gauge theory - the massive Schwinger model in various gauges is studied. A LF version of bosonization and the massive Thirring model are also discussed. A special chapter is devoted to the method of discretized light cone quantization and its application to calculations of the properties of quantum solitons. The problem of LF zero modes is illustrated with the example of the two-dimensional Yukawa model. Hamiltonian perturbation theory in the LF formulation is derived and applied to a few simple processes to demonstrate its advantages. As a byproduct, it is shown that the LF theory cannot be obtained as a "light-like" limit of the usual field theory quantized on an initial space-like surface. A simple LF formulation of the Higgs mechanism is then given. Since our intention was to provide a treatment of the light front quantization accessible to postgradual students, an effort was made to discuss most of the topics pedagogically and a number of technical details and derivations are contained in the appendices.

A Combined Spin-Flip and IP/EA Approach for Handling Spin and Spatial Degeneracies: Application to Double Exchange Systems

2018 ◽  
Author(s):  
Shannon Houck ◽  
Nicholas Mayhall
Keyword(s):  
Single Molecule ◽  
Double Exchange ◽  
Computational Effort ◽  
Strongly Correlated ◽  
Single Molecule Magnets ◽  
New Approach ◽  
Spin Flip ◽  
Model Hamiltonian ◽  
Simultaneous Existence ◽  
Exchange Parameters

<div>Many multiconfigurational systems, such as single-molecule magnets, are difficult to study using traditional computational methods due to the simultaneous existence of both spin and spatial degeneracies. In this work, a new approach termed n-spin-flip Ionization Potential/Electron Affinity (<i>n</i>SF-IP or <i>n</i>SF-EA) is introduced which combines the spin-flip method of Anna Krylov with particle-number changing IP/EA methods. We demonstrate the efficacy of the approach by applying it to the strongly-correlated N<sub>2</sub><sup>+</sup> as well as several double exchange systems. We also demonstrate that when these systems are well-described by a double exchange model Hamiltonian, only 1SF-IP/EA is required to extract the double exchange parameters and accurately predict energies for the low-spin states. This significantly reduces the computational effort for studying such systems. The effects of including additional excitations (using a RAS-<i>n</i>SF-IP/EA scheme) are also examined, with particular emphasis on hole and particle excitations.</div>

A Combined Spin-Flip and IP/EA Approach for Handling Spin and Spatial Degeneracies: Application to Double Exchange Systems

2018 ◽  
Author(s):  
Shannon Houck ◽  
Nicholas Mayhall
Keyword(s):  
Single Molecule ◽  
Double Exchange ◽  
Computational Effort ◽  
Strongly Correlated ◽  
Single Molecule Magnets ◽  
New Approach ◽  
Spin Flip ◽  
Model Hamiltonian ◽  
Simultaneous Existence ◽  
Exchange Parameters

<div>Many multiconfigurational systems, such as single-molecule magnets, are difficult to study using traditional computational methods due to the simultaneous existence of both spin and spatial degeneracies. In this work, a new approach termed n-spin-flip Ionization Potential/Electron Affinity (<i>n</i>SF-IP or <i>n</i>SF-EA) is introduced which combines the spin-flip method of Anna Krylov with particle-number changing IP/EA methods. We demonstrate the efficacy of the approach by applying it to the strongly-correlated N<sub>2</sub><sup>+</sup> as well as several double exchange systems. We also demonstrate that when these systems are well-described by a double exchange model Hamiltonian, only 1SF-IP/EA is required to extract the double exchange parameters and accurately predict energies for the low-spin states. This significantly reduces the computational effort for studying such systems. The effects of including additional excitations (using a RAS-<i>n</i>SF-IP/EA scheme) are also examined, with particular emphasis on hole and particle excitations.</div>

Addressing the Frenkel and charge transfer character of exciton states with a model Hamiltonian based on dimer calculations: Application to large aggregates of perylene bisimide

2021 ◽  
Vol 154 (12) ◽  
pp. 124101
Author(s):  
Sofia Canola ◽  
Giuseppe Bagnara ◽  
Yasi Dai ◽  
Gaetano Ricci ◽  
Alessandro Calzolari ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Perylene Bisimide ◽  
Model Hamiltonian

scholarly journals Magnon-polaron formation in XXZ quantum Heisenberg chains

2021 ◽  
Vol 103 (19) ◽  
Author(s):  
D. Morais ◽  
F. A. B. F. de Moura ◽  
W. S. Dias
Keyword(s):  
Heisenberg Chains ◽  
Polaron Formation

Polaron formation dynamics in conducting polymers

2007 ◽  
Vol 157 (8-9) ◽  
pp. 380-385 ◽  
Author(s):  
Xiaojing Liu ◽  
Kun Gao ◽  
Yuan Li ◽  
Jiyong Fu ◽  
Jianhua Wei ◽  
...  
Keyword(s):  
Conducting Polymers ◽  
Formation Dynamics ◽  
Polaron Formation

Tc IN MULTI-LAYER OXIDE SUPERCONDUCTORS

1989 ◽  
Vol 03 (01) ◽  
pp. 109-115 ◽  
Author(s):  
RUIBAO TAO ◽  
XIAO HU ◽  
MASUO SUZUKI
Keyword(s):  
Transition Temperature ◽  
Oxide Superconductors ◽  
Nearest Neighbour ◽  
Model Hamiltonian

A possible relation of the supeconducting transition temperature T c to the number of Cu-O planes coupled tightly in a Tl-Ca-Ba-Cu-O compound is discussed by means of Anderson's RVB theory. A model Hamiltonian has been suggested to include the tunneling of singlet pairs between the nearest neighbour Cu-O planes and our calculation shows that the experimental T c can be fitted well and raised obviously by increasing the number of Cu-O planes at first, then it becomes more and more insensitive as the number is increased beyond 4 or 5. The maximum T c may approach 144 K.

Molecular dynamics of pyrazine after excitation to the S2 electronic state using a realistic 24-mode model Hamiltonian

1999 ◽  
Vol 110 (2) ◽  
pp. 936-946 ◽  
Author(s):  
A. Raab ◽  
G. A. Worth ◽  
H.-D. Meyer ◽  
L. S. Cederbaum
Keyword(s):  
Molecular Dynamics ◽  
Electronic State ◽  
Model Hamiltonian
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