scholarly journals GREEN'S FUNCTIONS OF INFINITE-U ASYMMETRIC HUBBARD MODEL: FALICOV-KIMBALL LIMIT

2003 ◽  
Vol 6 (1) ◽  
pp. 127 ◽  
Author(s):  
Stasyuk ◽  
Hera
Keyword(s):  
Hubbard Model ◽  
Green's Functions ◽  
Green’S Functions ◽  
Asymmetric Hubbard Model

scholarly journals SPECTRAL FUNCTION OF A d-p HUBBARD MODEL

2011 ◽  
Vol 25 (01) ◽  
pp. 41-53 ◽  
Author(s):  
E. J. CALEGARI ◽  
S. G. MAGALHAES
Keyword(s):  
Correlation Function ◽  
Fermi Surface ◽  
Hubbard Model ◽  
Spectral Function ◽  
Coulomb Interaction ◽  
Green's Functions ◽  
Green’S Functions ◽  
Pole Approximation ◽  
Antiferromagnetic Correlations ◽  
Important Correlation

This work investigates a d-p Hubbard model by the n-pole approximation in the hole-doped regime. In particular, the spectral function A(ω, k) is analyzed varying the filling, the local Coulomb interaction and the d-p hybridization. It should be remarked that the original n-pole approximation (Phys. Rev.184, 451 1969) has been improved in order to include adequately the k-dependence of the important correlation function 〈Sj·Si〉 present in the poles of the Green's functions. It has been verified that the topology of the Fermi surface (defined by A(ω = 0, k)) is deeply affected by the doping, the strength of the Coulomb interaction and also by the hybridization. Particularly, in the underdoped regime, the spectral function A(ω = 0, k) presents very low intensity close to the antinodal points (0, ±π) and (±π, 0). Such a behavior produces an anomalous Fermi surface (pockets) with pseudogaps in the region of the antinodal points. On the other hand, if the d-p hybridization is enhanced sufficiently, such pseudogaps vanish. It is precisely the correlation function 〈Sj·Si〉, present in the poles of the Green's functions, plays an important role in the underdoped situation. In fact, antiferromagnetic correlations coming from 〈Sj·Si〉 strongly modify the quasiparticle band structure. This is the ultimate source of anomalies in the Fermi surface in the present approach.

scholarly journals Энергетический спектр и спектр оптического поглощения фуллерена С-=SUB=-28-=/SUB=- в модели Хаббарда

2020 ◽  
Vol 62 (11) ◽  
pp. 1960
Author(s):  
А.В. Силантьев
Keyword(s):  
Group Theory ◽  
Hubbard Model ◽  
Green's Functions ◽  
Green’S Functions ◽  
Analytical Form ◽  
Energy Spectra ◽  
Symmetry Groups ◽  
Energy States ◽  
Static Fluctuation

Anticommutator Green’s functions and energy spectra of fullerene C28 and endofullerene Zr@C28 with the Td symmetry groups have been obtained in an analytical form within the Hubbard model and static fluctuation approxima-tion. The energy states have been classified using the methods of group theory, and the allowed transitions in the energy spectra of fullerene C28 and endofull-erene Zr@C28 with the Td symmetry groups have been determined.

scholarly journals Энергетический спектр и спектр оптического поглощения фуллерена C-=SUB=-26-=/SUB=- в модели Хаббарда

2021 ◽  
Vol 63 (11) ◽  
pp. 1951
Author(s):  
А.В. Силантьев
Keyword(s):  
Group Theory ◽  
Hubbard Model ◽  
Green's Functions ◽  
Green’S Functions ◽  
Analytical Form ◽  
Energy Spectra ◽  
Symmetry Groups ◽  
Endohedral Fullerene ◽  
Energy States ◽  
Static Fluctuation

Anticommutator Green’s functions and energy spectra of fullerene C26 and endohedral fullerene U@C26 with the D3h symmetry groups have been obtained in an analytical form within the Hubbard model and static fluctuation ap-proximation. The energy states have been classified using the methods of group theory, and the allowed transitions in the energy spectra of molecules C26 and U@C26 with the D3h symmetry groups have been determined.

scholarly journals Энергетический спектр и спектр оптического поглощения фуллерена C-=SUB=-24-=/SUB=- в модели Хаббарда

2020 ◽  
Vol 62 (3) ◽  
pp. 473
Author(s):  
А.В. Силантьев
Keyword(s):  
Group Theory ◽  
Hubbard Model ◽  
Green's Functions ◽  
Green’S Functions ◽  
Analytical Form ◽  
Energy Spectra ◽  
Symmetry Groups ◽  
Static Fluctuation Approximation ◽  
Energy States ◽  
Static Fluctuation

Anticommutator Green’s functions and energy spectra of fullerene C24 with the D6, D6d, and Oh symmetry groups have been obtained in an analytical form within the Hubbard model and static fluctuation approximation. The energy states have been classified using the methods of group theory, and the allowed transitions in the energy spectra of fullerene C24 with the D6, D6d, and Oh symmetry groups have been determined.

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