Uniaxial compressions induced complementarity and anisotropic behaviors in CuVP 2 S 6 .

Uniaxial compressions in layered materials can change their electronic structures and properties. In this work, a bimetallic compound CuVP 2 S 6 is simulated by using Density Functional Theory (DFT) in the presence of uniaxial compressions. Our results clearly show vertical compressions could lead to anisotropic behaviors, which include the compression effect caused by interlayer compression and the anisotropy of intralayer stretching. The vertical compressions change the V-S bonds and the P-S bonds respectively in AA and AB structures. The complementarity between intralayer stretching and interlayer compression could also result in adjustable bandgaps and degeneracy breakdown of V atoms. Results from the electron localization function analysis demonstrate that the free electrons of AA and AB structures tend to delocalize, and ionic features in V-S bonds could be weakened with increasing vertical compressions. Moreover, the two internal binding energies of AA and AB structures and the charge density difference analysis show that the anisotropy in the intralayer stretch and the charge transfer between metal atoms and S atoms increases gradually.