11,435 research outputs found
Model Hamiltonian for strongly-correlated systems: Systematic, self-consistent, and unique construction
An interacting lattice model describing the subspace spanned by a set of
strongly-correlated bands is rigorously coupled to density functional theory to
enable ab initio calculations of geometric and topological material properties.
The strongly-correlated subspace is identified from the occupation number band
structure as opposed to a mean-field energy band structure. The self-consistent
solution of the many-body model Hamiltonian and a generalized Kohn-Sham
equation exactly incorporates momentum-dependent and crystal-symmetric
correlations into electronic structure calculations in a way that does not rely
on a separation of energy scales. Calculations for a multiorbital Hubbard model
demonstrate that the theory accurately reproduces the many-body polarization.Comment: 19 pages, 11 figure
Approximate formula for the macroscopic polarization including quantum fluctuations
The many-body Berry phase formula for the macroscopic polarization is
approximated by a sum of natural orbital geometric phases with fractional
occupation numbers accounting for the dominant correlation effects. This
reduced formula accurately reproduces the exact polarization in the
Rice-Mele-Hubbard model across the band insulator-Mott insulator transition. A
similar formula based on a one-body reduced Berry curvature accurately predicts
the interaction-induced quenching of Thouless topological charge pumping
Optimal Control of charge transfer
In this work, we investigate how and to which extent a quantum system can be
driven along a prescribed path in space by a suitably tailored laser pulse. The
laser field is calculated with the help of quantum optimal control theory
employing a time-dependent formulation for the control target. Within a
two-dimensional (2D) model system we have successfully optimized laser fields
for two distinct charge transfer processes. The resulting laser fields can be
understood as a complicated interplay of different excitation and de-excitation
processes in the quantum system
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