Speaker
Description
Recent development in the high-pressure physics provides us with a new class of the superconducting materials, namely with the hydrogen-rich materials, such as silane (SiH$_4$, transition temperature $T_c$=17~K at pressure $p$=96~GPa), hydrogen sulphide (H$_{2/3}$S, $T_c$=203~K @ 150~GPa) or hydrogen lanthanide (H$_{1-x}$La, $T_c$=274--286~K @ 210~GPa).
We investigate the versatility of the molecular-to-atomic transitions in one-, two-, and quasi-three-dimensional hydrogen systems, using our own original approach -- the Exact Diagonalization Ab-Initio (\textsc{edabi}) method. Starting from the extended Hubbard model, we examine an electron-correlation-driven conductivity connected with the creation of high-symmetry hydrogen molecular and atomic planes, as well as a series of both structural and electronic-in-nature quantum phase transitions.
We discuss the suppression of molecular nature in a reversed Peierls-like transition under high pressure, as well as the proper van-der-Waals-like effective interaction derived from the first principles of quantum mechanics.
Using effective electron-phonon Hamiltonian we estimate both the zero-point motion of the lattice ions, as well as the electron-lattice coupling. Next, by using the McMillan formula we estimate the superconducting transition temperature versus the effective pressure (external and/or chemical).
We acknowledge the support of National Science Centre (NCN) grant OPUS, No. UMO-2018/29/B/ST3/02646 and the European Regional Development Fund in the IT4Inno-va-tions national supercomputing center -- path to exascale project, project number CZ 02.1.01/-0.0-/0.0-/16-013/0001791 within the Operational Programme Research, Development and Education.
