3,646 research outputs found
Adiabatic corrections for velocity-gauge simulations of electron dynamics in periodic potentials
We show how to significantly reduce the number of energy bands required to
model the interaction of light with crystalline solids in the velocity gauge.
We achieve this by deriving analytical corrections to the electric current
density. These corrections depend only on band energies, the matrix elements of
the momentum operator, and the macroscopic vector potential. Thus, the
corrections can be evaluated independently from modeling the interaction with
light. In addition to improving the convergence of velocity-gauge calculations,
our analytical approach overcomes the long-standing problem of divergences in
expressions for linear and nonlinear susceptibilities.Comment: Submitted to Computer Physics Communication
QCD Sum Rules for Heavy Flavors
We give a short review of QCD sum rule results for B and D mesons and
Lambda_Q and Sigma_Q baryons. We focus mainly on recent developments concerning
semileptonic B->pion and D->pion transitions, pion couplings to heavy hadrons,
decay constants and estimates of the b quark mass from a baryonic sum rule, and
the extraction of the pion distribution amplitude from CLEO data.Comment: 12 pages, LaTeX, Talk given by O.Yakovlev at the 4th Workshop on
Continuous Advances in QCD, Minneapolis, May 12-14, 2000; to appear in the
Proceeding
- …