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

TL;DR

This study investigates how pressure induces phase transitions in layered FePSe3, altering its electronic structure and chemical bonding, with implications for its electronic properties and interatomic interactions.

Contribution

The paper provides a detailed topological analysis of chemical bonding changes in FePSe3 under pressure, revealing new insights into phase transition mechanisms and bond nature alterations.

Findings

Pressure induces symmetry changes at 6 GPa and 13 GPa.

Band gap collapse at 13 GPa due to atomic displacements.

Interlayer P-P interactions emerge after semiconductor-metal transition.

Abstract

Two pressure-induced phase transitions have been theoretically studied in the layered iron phosphorus triselenide (FePSe3). Topological analysis of chemical bonding in FePSe3 has been performed based on the results of first-principles calculations within the periodic linear combination of atomic orbitals (LCAO) method with hybrid Hartree-Fock-DFT B3LYP functional. The first transition at about 6 GPa is accompanied by the symmetry change from R-3 to C2/m, whereas the semiconductor-to-metal transition (SMT) occurs at about 13 GPa leading to the symmetry change from C2/m to P-31m. We found that the collapse of the band gap at about 13 GPa occurs due to changes in the electronic structure of FePSe3 induced by relative displacements of phosphorus or selenium atoms along the c-axis direction under pressure. The results of the topological analysis of the electron density and its Laplacian demonstrate that the pressure changes not only the interatomic distances but also the bond nature between the intralayer and interlayer phosphorus atoms. The interlayer P-P interactions are absent in two non-metallic FePSe3 phases while after SMT the intralayer P-P interactions weaken and the interlayer P-P interactions appear.