scholarly journals Quantum electrodynamics of atomic and molecular systems – Lesson 1

2012 ◽  
Author(s):  
Krzysztof Pachucki
Keyword(s):  
Quantum Electrodynamics ◽  
Molecular Systems

Molecular quantum electrodynamics

1971 ◽  
Vol 321 (1547) ◽  
pp. 557-572 ◽  
Keyword(s):  
Electromagnetic Field ◽  
Quantum Electrodynamics ◽  
Unitary Transformation ◽  
Charged Particles ◽  
Gauge Condition ◽  
Binding Energies ◽  
Quantum Mechanical ◽  
Supplementary Condition ◽  
Molecular Systems ◽  
Hamiltonian Theory

A comparison is made of the conventional quantum mechanical hamiltonian for the interaction of molecular systems with the electromagnetic field and the alternative multipole formulation given recently (Atkins & Woolley 1970). The conventional hamiltonian is first derived by using Dirac’s generalized hamiltonian theory in which the Coulomb gauge condition is introduced as a supplementary condition. We analyse further the interpretation of the unitary transformation that connects the two hamiltonians in terms of the arbitrariness of the phase of the wavefunctions of charged particles in the presence of the electromagnetic field, and finally examine the problem of exhibiting explicitly the binding energies of the molecular systems.

scholarly journals Derivation of the stationary fluorescence spectrum formula for molecular systems from the perspective of quantum electrodynamics

2021 ◽  
Vol 61 (2) ◽  
Author(s):  
Y. Braver ◽  
L. Valkunas ◽  
A. Gelzinis
Keyword(s):  
Fluorescence Spectrum ◽  
Quantum Electrodynamics ◽  
Fluorescence Spectra ◽  
Photon Emission ◽  
Mathematical Treatment ◽  
Matrix Formalism ◽  
Physical Content ◽  
Molecular Systems ◽  
Standard Textbook ◽  
Density Matrix Formalism

Numerical simulations of stationary fluorescence spectra of molecular systems usually rely on the relation between the photon emission rate and the system’s dipole–dipole correlation function. However, research papers usually take this relation for granted, and standard textbook expositions of the theory of fluorescence spectra also tend to leave out this important relation. In order to help researchers with less theoretical training gain a deeper understanding of the emission process, we perform a step-by-step derivation of the expression for the fluorescence spectrum, focusing on rigorous mathematical treatment and the underlying physical content. Right from the start, we employ quantum description of the electromagnetic field, which provides a clear picture of emission that goes beyond the phenomenological treatment in terms of the Einstein A coefficient. Having obtained the final expression, we discuss the relation of the latter to the present level of theory by studying a simple two-level system. From the technical perspective, the present work also aims at familiarizing the reader with the density matrix formalism and with the application of the double-sided Feynman diagrams.

A new classical method for dynamical calculation in molecular systems

1997 ◽  
Vol 90 (4) ◽  
pp. 599-609 ◽  
Author(s):  
NAĐA DOSLIC ◽  
S.DANKO BOSANAC
Keyword(s):  
Classical Method ◽  
Molecular Systems ◽  
Dynamical Calculation

Energy, Information, and Superluminal Speed in Quantum Electrodynamics

2020 ◽  
pp. 27-33
Author(s):  
Boris A. Veklenko
Keyword(s):  
Electromagnetic Field ◽  
Perturbation Theory ◽  
Quantum Electrodynamics ◽  
Excited Atom ◽  
Standard Quantum ◽  
Energy Information

Without using the perturbation theory, the article demonstrates a possibility of superluminal information-carrying signals in standard quantum electrodynamics using the example of scattering of quantum electromagnetic field by an excited atom.

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