Using density functional theory with added on-site interactions (DFT+U), we study the electronic structure of bulk, monolayer, and bilayer of the layered transition-metal dichalcogenide 1T−TaS2. We show that a two-dimensional spin--21 Mott-phase exists for the monolayer in the charge-density wave state (CDW) and that such a phase is systematically destroyed by packing of the distorted layers leading to a one dimensional metal for bulk, CDW-distorted TaS2. The latter finding is in contrast with previous DMFT predictions --disagreement we explain by the weak effective interaction felt by the electrons in the CDW state. Experimental observations of insulating behavior may arise from disorder due to stacking faults.
@article{arxiv.1401.0246,
title = {Three Dimensional Metallic and Two Dimensional Insulating Behavior in Tantalum Dichalcogenides},
author = {Pierre Darancet and Andrew J. Millis and Chris A. Marianetti},
journal= {arXiv preprint arXiv:1401.0246},
year = {2015}
}