Ievgeniia Savchenko

• The thesis is devoted to the understanding of the nuclear quantum effects and the underlying mechanism of the hydrogen isotopologues (D2/HD/H2) separation in metal-organic frameworks, which involves fundamentals of quantum mechanics. The thesis highlights the concept of nanoporous materials and specifically the relatively new class of crystalline compounds called metal-organic frameworks (MOFs). The accent is on the two types of MOFs. One type incorporates strongly unsaturated (also known as open) metal centers and the other possesses geometrically restricted, strongly confined pores. The metal centers and the defined pores are proven to be excellent sieves for the gas molecules. When exploiting the sieving in MOFs, we refer to the two main selective mechanisms for hydrogen isotopologues: Chemical Affinity Quantum Sieving (CAQS), which takes place when the highly attractive unsaturated metal centers are present and Kinetic Quantum Sieving (KQS), which occurs due to the strongly confined pores. The CAQS process is most pronounced at relatively high temperatures (100 K and above) while KQS manifest itself at nearly cryogenic temperature. The theoretical background of this work is based on the approximate solutions of the complex quantum-mechanical systems e.g. the adsorption of D2/HD/H2 and their separation in MOFs. This involves Born-Oppenheimer approximation of the time independent non-relativistic Schrödinger equation, the solutions to the electronic and nuclear parts of the Schrödinger equation incorporating ab initio quantum-mechanical calculations for electronic structure and the methods for treating nuclear quantum effects.