Effect of Uniaxial Strain on Band Structure of Multi-layer WS$_{\mathrm{2}}$*

The ability to tailor band structure of a multi-layer transition metal dichalcogenide is of interest because it opens up utilizations of the material for various applications. Strain is considered a robust way to alter the electronic structure of a material. We performed calculations, using density functional theory, of band structure of multi-layer WS$_{\mathrm{2}}$ under the effects of uniaxial strain. We show that the position of the bottom of conduction band (BCB) at $\sum $ moves to higher, and at K to lower, energy levels under the effects of uniaxial tensile strain, making multi-layer WS$_{\mathrm{2}}$ closer to a direct band gap material. Our results suggest that uniaxial tensile strain can be used to alter band structure of multi-layer WS$_{\mathrm{2}}$ to achieve higher yield photo luminescence.