Тип публикации: статья из журнала
Год издания: 2012
Идентификатор DOI: 10.1134/S1063776111150143
Ключевые слова: Calculated values, Cluster perturbation theories, Concentration dependence, Concentration region, Cuprates, Density of state, Dispersion relations, Energy resolutions, Exact diagonalization, Ground-state energies, Hole-doping, Hubbard X operators, In-gap state, Lower hubbard bands, Nonperturbative, Paramagnetic state, Parameter values, Pertubation theory, Quantum Monte Carlo methods, Spectral weight, Strong electron correlations, Variational Monte Carlo method, Copper compounds, Electronic structure, Fermi surface, Hubbard model, Monte Carlo methods, Paramagnetism, Spectral density, Hole concentration
Аннотация: 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 x 2 clusters. Representation of the Hubbard X operators makes it possible to control conservation of the spectral weight in coПоказать полностьюnstructing 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 x 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.
Журнал: JOURNAL OF EXPERIMENTAL AND THEORETICAL PHYSICS
Выпуск журнала: Vol. 114, Is. 1
Номера страниц: 118-131
ISSN журнала: 10637761
Место издания: NEW YORK
Издатель: MAIK NAUKA/INTERPERIODICA/SPRINGER