Strain control of the competition between metallic and semiconducting states in single-layers of TaSe3

TaSe3 is a metallic layered material whose structure is built from TaSe3 trigonal prismatic chains. In this work we report a first-principles density functional theory study of TaSe3 single-layers and we find that, despite the existence of non negligible SeSe interlayer interactions, TaSe3 single layers are metallic. However, an interesting competition between metallic and semiconducting states is found under the effect of strain. The single-layers keep the metallic behaviour under biaxial strain although the nature of the hole carriers changes. In contrast, uniaxial strain along the chains direction induces the stabilization of a semiconducting state. Potential electronic instabilities due to Fermi surface nesting are found for single-layers under either biaxial strain or uniaxial strain along the long (inter-chain) axis of the layers. Bilayers and trilayers have also been considered. The structural and electronic features behind these unexpected observations are analyzed.