Spin Effects in isolated mono- and bilayer molybdenum disulfide Nanowires*

Inspired by the recent synthesis of needle-like MoS$_2$ nanoparticles, we have investigated the properties of isolated quasi-one dimensional MoS$_2$ nanowires. These nanostructures deserve a special interest since they constitute one of the smallest self-supported MoS$_2$ systems with promising catalytic properties. A complete description of the edge, electronic and spin properties for different sulfur saturations is extremely important for the future developments of novel MoS$_2$-based nanocatalysts. In this work we have performed ab initio simulations within the Density Functional Theory framework with the \textsc{Siesta} code to study the structural, electronic and spin properties of quasi-one dimensional MoS$_2$ Nanostructures. We observed that a change in the number of Mo atoms on the unit cell affects greatly the electronic properties. Interestingly, metallic states are found in all the low-energy models. Also, both for mono- and bilayer the spin states are also localized at the active nanowire edges. We also noticed the presence of a variety of spin regimes suggesting the connection between magnetism and its catalytic properties. In spite of the observed pairing of S dimers at the Mo-edge in some cases, we do not observe a Peierls-like metal-insulator transition.