Nonadiabatic Dynamics in Si and CdSe Nanoclusters: Many-Body vs Single-Particle Treatment of Excited States

2021 ◽  
Vol 17 (2) ◽  
pp. 678-693
Author(s):  
Brendan Smith ◽  
Mohammad Shakiba ◽  
Alexey V. Akimov
Keyword(s):  
Excited States ◽  
Single Particle ◽  
Nonadiabatic Dynamics ◽  
Many Body

scholarly journals A Collective Rotational State of Spherical Nuclei

1976 ◽  
Vol 29 (5) ◽  
pp. 363 ◽  
Author(s):  
JR Henderson ◽  
J Lekner
Keyword(s):  
Angular Momentum ◽  
Excited States ◽  
Single Particle ◽  
First Principles ◽  
Finite System ◽  
Rotational Excitation ◽  
Many Body ◽  
Spurious State ◽  
System Of Particles ◽  
Spherical Nuclei

We consider a particular many-body rotational excitation 'P of a spherical self-bound system of particles, of the form studied by Lekner (1974). This angular momentum eigenstate is translationally invariant and thus is not a spurious state. The energy of 'P is found from first principles to be substantially larger than that of the first 2+ excited states of even-even nuclei, with the exception of 208Pb. The quadrupole moment is negative, the g-factor is approximately Z/A and the lifetime is shorter than the single-particle (Weisskopf) value by a factor of the order of A/Z2. It is suggested that these states are the finite system rotational analogues of Feynman's phonons and rotons.

Measurement of Ground State Magnetization Densities and the Excitation of High Multipolarity Magnetic Excitation of Single Particle

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Shad Husain
Keyword(s):  
Binding Energy ◽  
Excited States ◽  
Single Particle ◽  
Ground State ◽  
Nuclear Physics ◽  
Spherically Symmetric ◽  
Magnetic Excitation ◽  
Many Body ◽  
Ground State Binding Energy ◽  
Quantization Representation

This topic deals in the study of correlation of ground and excited states of even nuclei like 160 and 4He. The main objective of present work is to develop more theoretical techniques applicable in nuclear physics. The work is also extended to discrete excited states as well as odd even nuclei. The work is useful for the calculation of nuclear many body problems for spherically symmetric nuclear quantization representation. The ground state calculation of 160 and 4He are done using G. matrix, which also help in calculation of ground state binding energy and one body two body densities.

A multi-layer energy-based fragment method for excited states and nonadiabatic dynamics

2019 ◽  
Vol 21 (41) ◽  
pp. 22695-22699 ◽  
Author(s):  
Wen-Kai Chen ◽  
Wei-Hai Fang ◽  
Ganglong Cui
Keyword(s):  
Excited States ◽  
Nonadiabatic Dynamics ◽  
Many Body ◽  
The Many ◽  
Body Energy ◽  
Fragment Method ◽  
Energy Expansion

We developed a multi-layer energy-based fragment (MLEBF) method within the many-body energy expansion framework.

QLB for Quantum Many-Body and Quantum Field Theory

2018 ◽  
Author(s):  
Sauro Succi
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Quantum Mechanics ◽  
Quantum Computing ◽  
Single Particle ◽  
Body Problem ◽  
Three Dimensions ◽  
Quantum Field ◽  
Many Body ◽  
Quantum Particles

Chapter 32 expounded the basic theory of quantum LB for the case of relativistic and non-relativistic wavefunctions, namely single-particle quantum mechanics. This chapter goes on to cover extensions of the quantum LB formalism to the overly challenging arena of quantum many-body problems and quantum field theory, along with an appraisal of prospective quantum computing implementations. Solving the single particle Schrodinger, or Dirac, equation in three dimensions is a computationally demanding task. This task, however, pales in front of the ordeal of solving the Schrodinger equation for the quantum many-body problem, namely a collection of many quantum particles, typically nuclei and electrons in a given atom or molecule.

High-Fidelity First Principles Nonadiabaticity: Diabatization, Analytic Representation of Global Diabatic Potential Energy Matrices, and Quantum Dynamics

2021 ◽  
Author(s):  
Yafu Guan ◽  
Changjian Xie ◽  
David R. Yarkony ◽  
Hua Guo
Keyword(s):  
Potential Energy ◽  
Excited States ◽  
First Principles ◽  
Quantum Dynamics ◽  
Chemical Processes ◽  
High Fidelity ◽  
Nonadiabatic Dynamics ◽  
Electronically Excited States ◽  
Electronically Excited ◽  
Oppenheimer Approximation

Nonadiabatic dynamics, which goes beyond the Born-Oppenheimer approximation, has increasingly been shown to play an important role in chemical processes, particularly those involving electronically excited states. Understanding multistate dynamics requires...

scholarly journals Excited state Rényi entropy and subsystem distance in two-dimensional non-compact bosonic theory. Part I. Single-particle states

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Jiaju Zhang ◽  
M.A. Rajabpour
Keyword(s):  
Excited States ◽  
Single Particle ◽  
Renyi Entropy ◽  
Rényi Entropy ◽  
Large Momentum ◽  
Particle State ◽  
Two Dimensional ◽  
Universal Form ◽  
Conformal Field ◽  
Harmonic Chain

Abstract We investigate the Rényi entropy of the excited states produced by the current and its derivatives in the two-dimensional free massless non-compact bosonic theory, which is a two-dimensional conformal field theory. We also study the subsystem Schatten distance between these states. The two-dimensional free massless non-compact bosonic theory is the continuum limit of the finite periodic gapless harmonic chains with the local interactions. We identify the excited states produced by current and its derivatives in the massless bosonic theory as the single-particle excited states in the gapless harmonic chain. We calculate analytically the second Rényi entropy and the second Schatten distance in the massless bosonic theory. We then use the wave functions of the excited states and calculate the second Rényi entropy and the second Schatten distance in the gapless limit of the harmonic chain, which match perfectly with the analytical results in the massless bosonic theory. We verify that in the large momentum limit the single-particle state Rényi entropy takes a universal form. We also show that in the limit of large momenta and large momentum difference the subsystem Schatten distance takes a universal form but it is replaced by a new corrected form when the momentum difference is small. Finally we also comment on the mutual Rényi entropy of two disjoint intervals in the excited states of the two-dimensional free non-compact bosonic theory.

scholarly journals Feynman diagrams and rooted maps

Open Physics ◽  
2018 ◽  
Vol 16 (1) ◽  
pp. 149-167 ◽  
Author(s):  
Andrea Prunotto ◽  
Wanda Maria Alberico ◽  
Piotr Czerski
Keyword(s):  
Single Particle ◽  
Feynman Diagram ◽  
Feynman Diagrams ◽  
Topological Properties ◽  
Many Body ◽  
Perturbative Order ◽  
Original Definition ◽  
Many Body Systems ◽  
Definition Of ◽  
Particle Propagator

Abstract The rooted maps theory, a branch of the theory of homology, is shown to be a powerful tool for investigating the topological properties of Feynman diagrams, related to the single particle propagator in the quantum many-body systems. The numerical correspondence between the number of this class of Feynman diagrams as a function of perturbative order and the number of rooted maps as a function of the number of edges is studied. A graphical procedure to associate Feynman diagrams and rooted maps is then stated. Finally, starting from rooted maps principles, an original definition of the genus of a Feynman diagram, which totally differs from the usual one, is given.

A SOLVABLE MODEL OF INTERACTING MANY BODY SYSTEMS EXHIBITING A BREAKDOWN OF THE BOLTZMANN EQUATION

2014 ◽  
Vol 28 (03) ◽  
pp. 1450046
Author(s):  
B. H. J. McKELLAR
Keyword(s):  
Boltzmann Equation ◽  
Time Dependence ◽  
Single Particle ◽  
Density Operator ◽  
Particle Density ◽  
Solvable Model ◽  
Many Body ◽  
Single Particle Density ◽  
The Boltzmann Equation ◽  
Many Body Systems

In a particular exactly solvable model of an interacting system, the Boltzmann equation predicts a constant single particle density operator, whereas the exact solution gives a single particle density operator with a nontrivial time dependence. All of the time dependence of the single particle density operator is generated by the correlations.

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