Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Influence of next-nearest-neighbor electron hopping on the static and
  dynamical properties of the 2D Hubbard model   Comparing experimental data for high temperature cuprate superconductors with
numerical results for electronic models, it is becoming apparent that a hopping
along the plaquette diagonals has to be included to obtain a quantitative
agreement. According to recent estimations the value of the diagonal hopping
$t'$ appears to be material dependent. However, the values for $t'$ discussed
in the literature were obtained comparing theoretical results in the weak
coupling limit with experimental photoemission data and band structure
calculations. The goal of this paper is to study how $t'$ gets renormalized as
the interaction between electrons, $U$, increases. For this purpose, the effect
of adding a bare diagonal hopping $t'$ to the fully interacting two dimensional
Hubbard model Hamiltonian is investigated using numerical techniques. Positive
and negative values of $t'$ are analyzed. Spin-spin correlations, $n(\bf{k})$,
$\langle n\rangle$ vs $\mu$, and local magnetic moments are studied for values
of $U/t$ ranging from 0 to 6, and as a function of the electronic density. The
influence of the diagonal hopping in the spectral function $A(\bf{k},\omega)$
is also discussed, and the changes in the gap present in the density of states
at half-filling are studied. We introduce a new criterion to determine probable
locations of Fermi surfaces at zero temperature from $n(\bf{k})$ data obtained
at finite temperature. It appears that hole pockets at ${\bf{k}}=(\pi/2,\pi/2)$
may be induced for negative $t'$ while a positive $t'$ produces similar
features at ${\bf{k}}=(\pi,0)$ and $(0,\pi)$. Comparisons with the standard 2D
Hubbard ($t'=0$) model indicate that a negative $t'$ hopping amplitude appears
to be dynamically generated. In general, we conclude that it is very dangerous
to extract a bare parameter of the Hamiltonian $(t')$ from PES data where

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The categories of this paper are: astro-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: chem-ph
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The categories of this paper are: nlin
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The categories of this paper are: hep-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: adap-org
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The categories of this paper are: plasm-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: econ
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The categories of this paper are: solv-int
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The categories of this paper are: q-alg
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The categories of this paper are: funct-an
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The categories of this paper are: atom-ph
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The categories of this paper are: math-ph
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The categories of this paper are: eess