The main scientific interest of the Theory of Quantum Systems group is related with the modeling of nano- and mesoscopic systems. The area of ​​interest includes unconventional states of matter in highly correlated electron systems (high-temperature superconductors and magic-angle twisted bilayer graphene), solid hydrogen phases (molecular and its metallization), as well as metallic nanofims and oxide interfaces. The group also studies the phenomena related to electron transport in nanoscopic semiconductor structures and semiconductor-superconductor hybrids in the context of understanding the fundamental properties of exotic quasiparticles, and construction of next-generation electronics. The methods and computational packages used in our research are: the renormalized mean field theory (RMFT), the diagrammatic expansion of the Gutzwiller wave function method (DE-GWF), the variational quantum Monte Carlo method (VMC), the EDABI method (Exact Diagonalization Ab Initio Approach), VASP, WANNIER90, as well as the kwant library. We use self-written codes, computational packages and modern environments for remote work. TeraACMiN high performance cluster is used in the conducted research.