Final Report Summary - FEMTO/NANO (Nonequilibrium phenomena at femtosecond/nanometer scale) To reach the aim of the project, namely, to develop the theory of quantum dynamics and non-equilibrium properties at the nanoscale, one has to combine methodical work with applications to real, practically and theoretically important systems. During the project time, the following approaches have been developed and successfully applied:(1) Dual fermion and dual boson techniques for strongly correlated systems. General concept was suggested earlier by the principal investigator and coauthors but now it is transformed to a powerful computational tool, together with better understanding of its mathematical structure and formal properties. As a result, the first consistent theory for plasmons in strongly correlated systems has been developed, and the novel physical phenomenon, a formation of flat bands near Lifshitz transition points in strongly correlated systems was theoretically predicted and studied. A review on the method is published (Rev. Mod. Phys. 90, 025003 (2018)). (2) Tight-binding propagation model, suggested earlier in the group of the principal investigator, was essentially improved and applied to a series of timely physical problems such as electronic structure and transport properties of Van der Waals heterostructures graphene/boron nitride, few-layer black phosphorus, single-layer antimonene and arsenene and semiconducting heterostructures with fractal geometry. (3) Electronic structure and magnetic properties of magnetic molecules and clusters have been studied. It was demonstrated, in particular, that exchange magnetic interactions in rare-earth clusters may be dramatically different from those in the bulk rare-earth metals. Probably, the most important achievement in this direction is a completely first-principle description of magnetic interactions and spin excitations in the prototype molecular magnet, Mn12. (4) Quantum dynamics of spin systems after measurement was systematically studied. This allows to check basic concepts such as pointer states, decoherence waves, quantum Zeno effect. Novel effects are predicted such as formation of Neel antiferromagnetic state by repeating local measurements which can be checked via time-dependent scanning tunneling microscopy measurements. (5) Consistent, mathematically accurate theory of semiclassical dynamics of Dirac fermions is developed and applied to a complete analysis of electronic optics in graphene.
