Speaker
Shiwei Zhang
Description
I will describe recent progress in developing a general
framework for accurate ground-state calculations of
interacting electronic systems. This framework is based on
the use of auxiliary-fields, and addresses the sign problem
(which turns into a phase problem for realistic
electron-electron interactions) by constraining the
imaginary-time
paths with an approximate sign (gauge) condition. The
approach can be used to study either a fully
materials-specific Hamiltonian or a Hubbard-like model ---
or indeed any electronic Hamiltonian in between as the
former is ``down-folded'' to the latter.
As an example of materials-specific calculations, we
determine the equation of state in a variety of solids,
which systematically removes deficiencies of
density-functional theory (DFT) results. As an example of
model studies, the nature of magnetic and charge
correlations in the doped Hubbard model are determined, in
the context of models for high-temperature
superconductivity. Its implications on the search for
so-called FFLO phases with cold atoms will be discussed.
We also present exact results on the properties of the
two-dimensional ultracold Fermi gas. Calculations in systems
with strong spin-orbit coupling will be discussed.
