Search results for "Diabatic"
showing 3 items of 303 documents
Merging Features from Green's Functions and Time Dependent Density Functional Theory: A Route to the Description of Correlated Materials out of Equil…
2016
We propose a description of nonequilibrium systems via a simple protocol that combines exchange-correlation potentials from density functional theory with self-energies of many-body perturbation theory. The approach, aimed to avoid double counting of interactions, is tested against exact results in Hubbard-type systems, with respect to interaction strength, perturbation speed and inhomogeneity, and system dimensionality and size. In many regimes, we find significant improvement over adiabatic time dependent density functional theory or second Born nonequilibrium Green's function approximations. We briefly discuss the reasons for the residual discrepancies, and directions for future work.
Quantum Information by Adiabatic Passage : Quantum Gates and Decoherence
2007
The first part of this thesis is about adiabatic quantum processes designed for the implementation of quantum logic gates, the elementary components of quantumcomputers, by the interaction of pulsed laser fields with atoms. The adiabaticmethods allow robust processes, i.e. which are not sensitive to the fluctuationsof experimental parameters. The processes described in this thesis only requireaccurate control of the polarisations and the relative static phases of thelaser fields. These processes allow the implementation of a universal set ofquantum gates, which make possible the implementation of all the other quantumgates by combinations.The second part of this thesis concerns the effects …
Strictly correlated electrons approach to excitation energies of dissociating molecules
2019
In this work we consider a numerically solvable model of a two-electron diatomic molecule to study a recently proposed approximation based on the density functional theory of so-called strictly correlated electrons (SCE). We map out the full two-particle wave function for a wide range of bond distances and interaction strengths and obtain analytic results for the two-particle states and eigenenergies in various limits of strong and weak interactions, and in the limit of large bond distance. We then study the so-called Hartree-exchange-correlation (Hxc) kernel of time-dependent density functional theory which is a key ingredient in calculating excitation energies. We study an approximation b…