Structural instability of the ground state of the U2Mo compound

TL;DR

This study reveals the structural instability of U2Mo in the C11b phase at zero temperature, caused by a D6 distortion leading to a Peierls distortion and a different ground state structure than previously assumed.

Contribution

It demonstrates the electronic origin of the instability and identifies a new ground state structure for U2Mo beyond the traditional C11b phase.

Findings

D6 distortion induces a Peierls distortion in U2Mo.

The ground state structure of U2Mo differs from the assumed C11b phase.

Hybridization changes stabilize the distorted structure.

Abstract

This work reports the structural instability at T=0 K of the U2Mo compound in the structure C11b under the distortion related to the C66 elastic constant. The electronic properties of U2Mo such density of states (DOS), bands and Fermi surface (FS) are studied to understand the source of the instability. The C11b structure can be interpreted as formed by parallel linear chains along the z-directions each one composed by successive U-Mo-U blocks. The hybridization due to electronic interactions inside the U-Mo-U blocks is slightly modified under the D6 distortion. The change in distance among chains modifies the U-U interaction and produces the split of f-states. The distorted structure is stabilized by the energy lowering of the hybridized states, mainly between d-Mo and f-U states, together with the f-band split. Consequently, an induced Peierls distortion is produced in U2Mo due to the D6 distortion. In addition, the results of this work remarks that the structure of the ground state of the U2Mo compound is other than the assumed C11b structure.