Seminários

Seminário de Física da Matéria Condensada

Nesta quinta-feira (04/04) às 11h na sala 429 (torre nova) teremos o
seminário do palestrante Bruno Max de Souza Melo. São todos muito bem
vindos!
Segue abaixo o título e resumo:

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Palestrante: Bruno Max de Souza Melo (UFF)

Titulo: Single impurity Anderson model: a case study for different
impurity solvers

Resumo: The single impurity Anderson model (SIAM) is one of the most
recurrent model Hamiltonians in the study of a huge variety of
strongly correlated systems such as strongly interacting quantum dots,
doped metals with magnetic impurities, rare-earth compounds, etc.. In
this work we assess the reliability of some impurity solvers for the
SIAM, namely, the equations of motion (EOM) method, the numerical
renormalization group (NRG), the  non-crossing approximation (NCA),
and the one crossing approximation (OCA). First, we study the Green's
function of a quantum dot using the aforementioned impurity solvers
and then calculate the density of states as well as the zero bias
conductance as a function of the temperature of the quantum dot in the
wide band limit for a variety of scenarios . Our analysis is focused
on the Coulomb blockade and the Kondo physics. We report that some
standard approximations based on the EOM technique display a rather
unexpected poor behaviour in the Coulomb blockade regime even at high
temperatures. Next we study the Hubbard model applied to a hypercubic
lattice and compute the density of states of the model using the DMFT
combined with EOM, NCA, and OCA as impurity solvers paying particular
attention to the physics of the Mott metal-insulator transition. We
also present an evolution of the density of states as the local
Coulomb interaction is increased comparing the main features of the
transition displayed in each method. We discuss the applicability of
each method based on our results and on the previous ones reported in
the literature over the years.