Origin of pressure‐induced insulator‐to‐metal transition in the van der Waals compound FePS₃ from first‐principles calculations

Abstract

Pressure-induced insulator-to-metal transition (IMT) has been studied in the van der Waals compound iron thiophosphate (FePS 3 ) using first-principles calculations within the periodic linear combination of atomic orbitals method with hybrid Hartree-Fock-DFT B3LYP functional. Our calculations reproduce correctly the IMT at 15 GPa, which is accompanied by a reduction of the unit cell volume and of the vdW gap. We found from the detailed analysis of the projected density of states that the 3p states of phosphorus atoms contribute significantly at the bottom of the conduction band.As a result, the collapse of the band gap occurs due to changes in the electronic structure of FePS 3 induced by relative displacements of phosphorus or sulfur atoms along the c-axis direction under pressure. K E Y W O R D SFePS 3 , first principles calculations, high pressure, insulator-to-metal transition, layered compound

Topological analysis of chemical bonding in the layered FePSe3 upon pressure‐induced phase transitions

“…Moreover, similar to the case of FePS 3 , [42] metallic conductivity in FePSe 3 could also occur in the LP and HP-I phases if the P and Se atoms were located almost in the same plane.…”

“…In our preceding study, [ 42 ] we considered the pressure‐induced SMT in the crystalline iron thiophosphate (FePS 3 ) using first‐principles DFT calculations, which confirmed the experimentally found SMT at about 15 GPa. Moreover, we found from the detailed analysis of the projected density of states that the 3p states of phosphorus atoms contribute significantly at the bottom of the conduction band, and the effect can be tuned by the relative displacement of phosphorus or sulfur atoms along the c ‐axis.…”

“…The top of the valence bands in the LP and HP-I phases is mainly composed of the 3d(Fe) and 4p(Se) states, whereas the bottom of the conduction bands originates mainly from 3d(Fe), 3p(P) and 4p(Se) states. The contribution of the phosphorus atoms becomes particularly important in the HP-II phase, similarly to the case of FePS 3 42. Again, we found that the position of the phosphorus atoms, relative to the layer composed of the selenium atoms, is crucial for SMT.…”

“…The agreement between the theoretical and experimentally observed [58,59] phonon frequencies in the LP phase is good ( where phosphorous atoms move to the sulfur plane. [42] Such displacement leads to an increase of the distance between two intralayer similarly to the case of FePS 3 . [42] Again, we found that the position of the phosphorus atoms, relative to the layer composed of the selenium atoms, is crucial for SMT.…”

“…[42] Such displacement leads to an increase of the distance between two intralayer similarly to the case of FePS 3 . [42] Again, we found that the position of the phosphorus atoms, relative to the layer composed of the selenium atoms, is crucial for SMT.…”