Abstract Eitam Arnon

An ab initio Langevin dynamics approach is developed based on the stochastic density functional theory (sDFT) * within a new embedded fragment formalism. The forces on the nuclei generated by the stochastic DFT contain a random component which is used to estimate the friction term on each atom by satisfying the fluctuation–dissipation relation. The approach scales linear with the system size regardless of nearsightedness of the density matrix, and thus is applicable to ordered as well as disordered extended systems. We implement the approach for a series of silicon nanocrystals (NCs) of varying size up to 3 nm in diameter and over 3000 electrons and generate a set of configurations which are distributed canonically at a fixed temperature ranging from cryogenic to room temperature. We also analyze the structure properties and the NCs and discuss the reconstruction of the surface geometry.

* Roi Baer, Daniel Neuhauserand Eran Rabani: “Self-Averaging Stochastic Kohn-Sham Density-Functional Theory”; Phys. Rev. Lett.; 111, S. 106402 (2013).

Abstract Roie Dann

We describe a laser cooling mechanism based on many body effects. The mechanism is based on the collective behaviour of particle and light media. It relies on stochastic occurrences giving rise to an energy transfer between both media, resulting in an increase of entropy of the EM field on account of the particles kinetic energy. The method can be generalized for different atoms and molecules by adding another laser source inducing an AC stark effect. Simulations of phase space distributions where calculated comparing different particle densities, trap potentials and external source intensity profiles. The modelling shows efficient cooling rates up to 102K/s for a dense ensemble of Rb87 atoms, and cooling rates up to 6 · 102K/s when adding an additional source