63,736 research outputs found
Scaling Between Periodic Anderson and Kondo Lattice Models
Continuous-Time Quantum Monte Carlo (CT-QMC) method combined with Dynamical
Mean Field Theory (DMFT) is used to calculate both Periodic Anderson Model
(PAM) and Kondo Lattice Model (KLM). Different parameter sets of both models
are connected by the Schrieffer-Wolff transformation. For degeneracy N=2, a
special particle-hole symmetric case of PAM at half filling which always fixes
one electron per impurity site is compared with the results of the KLM. We find
a good mapping between PAM and KLM in the limit of large on-site Hubbard
interaction U for different properties like self-energy, quasiparticle residue
and susceptibility. This allows us to extract quasiparticle mass
renormalizations for the f electrons directly from KLM. The method is further
applied to higher degenerate case and to realsitic heavy fermion system CeRhIn5
in which the estimate of the Sommerfeld coefficient is proven to be close to
the experimental value
Phase equilibrium in two orbital model under magnetic field
The phase equilibrium in manganites under magnetic field is studied using a
two orbital model, based on the equivalent chemical potential principle for the
competitive phases. We focus on the magnetic field induced melting process of
CE phase in half-doped manganites. It is predicted that the homogenous CE phase
begins to decompose into coexisting ferromagnetic phase and CE phase once the
magnetic field exceeds the threshold field. In a more quantitative way, the
volume fractions of the two competitive phases in the phase separation regime
are evaluated.Comment: 4 pages, 4 figure
Optical Response of Solid CO as a Tool for the Determination of the High Pressure Phase
We report first-principles calculations of the frequency dependent linear and
second-order optical properties of the two probable extended-solid phases of
CO--V, i.e. and . Compared to the parent
phase the linear optical susceptibility of both phases is much smaller. We find
that and differ substantially in their linear optical
response in the higher energy regime. The nonlinear optical responses of the
two possible crystal structures differ by roughly a factor of five. Since the
differences in the nonlinear optical spectra are pronounced in the low energy
regime, i.e. below the band gap of diamond, measurements with the sample inside
the diamond anvil cell are feasible. We therefore suggest optical experiments
in comparison with our calculated data as a tool for the unambiguous
identification of the high pressure phase of CO.Comment: 4 pages 2 fig
Improving Stochastic Estimator Techniques for Disconnected Diagrams
Disconnected diagrams are expected to be sensitive to the inclusion of
dynamical fermions. We present a feasibility study for the observation of such
effects on the nucleonic matrix elements of the axial vector current, using
SESAM full QCD vacuum configurations with Wilson fermions on
lattices, at . Starting from the standard methods developed by the
Kentucky and Tsukuba groups, we investigate the improvement from various
refinements thereof.Comment: One author added. Contribution to Lattice 1997, 3 pages LaTex, to
appear in Nucl. Phys. B (Proc. Suppl.
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