Ground state of a dissipative two-level system: Coupled-cluster approximation

1996 ◽  
Vol 54 (18) ◽  
pp. 12859-12865 ◽  
Author(s):  
W. H. Wong ◽  
C. F. Lo
Keyword(s):  
Ground State ◽  
Coupled Cluster ◽  
Level System ◽  
Cluster Approximation

OPTIMAL COUPLED-CLUSTER APPROXIMATION FOR THE E⊗(b1+b2) JAHN–TELLER EFFECT

2005 ◽  
Vol 19 (30) ◽  
pp. 4495-4515
Author(s):  
L. P. LO ◽  
C. F. LO
Keyword(s):  
Ground State ◽  
Teller Effect ◽  
Coupled Cluster ◽  
Mathematical Treatment ◽  
Cluster Approximation ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Interacting Systems ◽  
Coupling Strengths ◽  
Better Than

In this work we have applied the optimal coupled-cluster approximation to study the ground state of the E⊗(b1+b2) Jahn–Teller effect. The effectiveness of the optimal coupled-cluster approximation has been investigated for the whole range of the asymmetry parameter and various coupling strengths. It is shown that our results up to the third level of approximation are in very good agreement with the exact numerical diagonalization results and are better than those from earlier variational treatments. Furthermore, unlike previous variational treatments, the optimal coupled-cluster approximation has the advantage that the accuracy of both the ground state energy and wavefunction estimates is being taken care of and can be systematically improved. Since the mathematical treatment in this work is simple, the optimal coupled-cluster approximation could be easily extended to the studies of other fermion-boson interacting systems, e.g. the extended Jahn–Teller system.

scholarly journals Effect of Fano Resonance in photovoltaic

2014 ◽  
Vol 2 (1) ◽  
Author(s):  
Dong Sun
Keyword(s):  
Ground State ◽  
Fano Resonance ◽  
Coupling Parameter ◽  
Level System ◽  
Decay Channels ◽  
Atomic Systems ◽  
Absorption And Emission ◽  
Fano Interference ◽  
Detail Balance ◽  
Ground State Doublet

AbstractWe have shown that the Fano interference in the decay channels of a three-level system can lead to considerably different absorption and emission profiles. We found that a coherence can be built up in the ground state doublet, with strength depending on a coupling parameter that arises from the Fano interference. The coherence can in principle lead to breaking of the detail balance between the absorption and emission processes in atomic systems.

Coherence preservation in 3-level atom

2011 ◽  
Vol 11 (5&6) ◽  
pp. 420-433
Author(s):  
Fei Yang ◽  
Shuang Cong
Keyword(s):  
Ground State ◽  
Numerical Experiments ◽  
Control Object ◽  
System Model ◽  
Level System ◽  
Multilevel System ◽  
Control Field ◽  
Object A ◽  
Breakdown Time ◽  
Level Atom

Coherence preservation of a multilevel system subject to Markovian decoherence is studied. A Lambda-type three-level atom is selected as the system model. Coherence preservation between a ground state and the excited state of such a system is defined as the control object. A control field is designed by means of constraining the constant coherence condition. For the singularities of the control field, we qualitatively analyze the breakdown time, i.e. the time of control diverging. We obtain the region in which the state stays to maintain coherence forever in the case that the three-level system is reduced to a two-level one. For other cases, we investigate how different parameters affect the breakdown time qualitatively. Numerical experiments are implemented on a three-level quantum system and the experimental results are analyzed.

Application of multireference linearized coupled-cluster theory to atomic and molecular systems

2018 ◽  
Vol 17 (02) ◽  
pp. 1850016 ◽  
Author(s):  
Jiang Yi ◽  
Feiwu Chen
Keyword(s):  
Ground State ◽  
Basis Sets ◽  
Coupled Cluster ◽  
Vibration Frequencies ◽  
Electron Affinities ◽  
Proton Affinities ◽  
Coupled Cluster Theory ◽  
Molecular Systems ◽  
Ground State Energies ◽  
Second Order Perturbation Theory

Applications of the multireference linearized coupled-cluster single-doubles (MRLCCSD) to atomic and molecular systems have been carried out. MRLCCSD is exploited to calculate the ground-state energies of HF, H2O, NH3, CH4, N2, BF, and C2with basis sets, cc-pVDZ, cc-pVTZ and cc-pVQZ. The equilibrium bond lengths and vibration frequencies of HF, HCl, Li2, LiH, LiF, LiBr, BH, and AlF are computed with MRLCCSD and compared with the experimental data. The electron affinities of F and CH as well as the proton affinities of H2O and NH3are also calculated with MRLCCSD. These results are compared with the results produced with second-order perturbation theory, linearized coupled-cluster doubles (LCCD), coupled-cluster doubles (CCD), coupled-cluster singles and doubles (CCSD), CCSD with perturbative triples correction (CCSD(T)). It is shown that all results obtained with MRLCCSD are reliable and accurate.

scholarly journals Complex ground-state and excitation energies in coupled-cluster theory

2021 ◽  
pp. e1968056
Author(s):  
Simon Thomas ◽  
Florian Hampe ◽  
Stella Stopkowicz ◽  
Jürgen Gauss
Keyword(s):  
Ground State ◽  
Coupled Cluster ◽  
Excitation Energies ◽  
Coupled Cluster Theory ◽  
Cluster Theory

scholarly journals Gaussian-Based Coupled-Cluster Theory for the Ground-State and Band Structure of Solids

2017 ◽  
Vol 13 (3) ◽  
pp. 1209-1218 ◽  
Author(s):  
James McClain ◽  
Qiming Sun ◽  
Garnet Kin-Lic Chan ◽  
Timothy C. Berkelbach
Keyword(s):  
Band Structure ◽  
Ground State ◽  
Coupled Cluster ◽  
Coupled Cluster Theory ◽  
Cluster Theory
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