Effect of hole doping on the electronic structure and the Fermi surface in the Hubbard model within norm-conserving cluster pertubation theory |
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Authors: | S V Nikolaev S G Ovchinnikov |
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Institution: | 1.Kirensky Institute of Physics, Siberian Branch,Russian Academy of Sciences,Krasnoyarsk,Russia;2.Dostoevsky State University,Omsk,Russia;3.Siberian Federal University,Krasnoyarsk,Russia |
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Abstract: | The concentration dependences of the band structure, spectral weight, density of states, and Fermi surface in the paramagnetic
state are studied in the Hubbard model within cluster pertubation theory with 2 × 2 clusters. Representation of the Hubbard
X operators makes it possible to control conservation of the spectral weight in constructing cluster perturbation theory. The
calculated value of the ground-state energy is in good agreement with the results obtained using nonperturbative methods such
as the quantum Monte Carlo method, exact diagonalization of a 4 × 4 cluster, and the variational Monte Carlo method. It is
shown that in the case of hole doping, the states in the band gap (in-gap states) lie near the top of the lower Hubbard band
for large values of U and near the bottom of the upper band for small U. The concentration dependence of the Fermi surface strongly depends on hopping to second (t′) and third (t″) neighbors. For parameter values typical of HTSC cuprates, the existence of three concentration regions with different Fermi
surfaces is demonstrated. It is shown that broadening of the spectral electron density with an energy resolution typical of
contemporary ARPES leads to a pattern of arcs with a length depending on the concentration. Only an order-of-magnitude decrease
in the linewidth makes it possible to obtain the true Fermi surface from the spectral density. The kinks associated with strong
electron correlations are detected in the dispersion relation below the Fermi level. |
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