Topological Phase Transition in the SmS Kondo Insulator under pressure

Employing LDA$+U $electronic structure calculations we predict that SmS undergoes a topological phase transition from the trivial Kondo insulator (KI) black phase to a topological metallic gold phase under hydrostatic pressure. The underlying mechanism is the pressure-induced change of the 4$f $level from below to above the bottom of the 5$d$ conduction band, leading to a \textit{df} band inversion, a parity sign reversal, and the concomitant change of the topological invariant. This provides the first material realization of the topological classification of KIs proposed by Dzero \textit{et al}.