Charge density waves are ubiquitous phenomena in metallic transition metal dichalcogenides. In NbSe2, a triangular 3×3 structural modulation is coupled to a charge modulation. Recent experiments reported evidence for a triangular-stripe transition at the surface, due to strain or accidental doping and associated to a 4×4 modulation. We employ \textit{ab-initio} calculations to investigate the strain-induced structural instabilities in a pristine single layer and analyse the energy hierarchy of the structural and charge modulations. Our results support the observation of phase separation between triangular and stripe phases in 1H-NbSe2, relating the stripe phase to compressive isotropic strain, favouring the 4×4 modulation. The observed wavelength of the charge modulation is also reproduced with good accuracy.
@article{arxiv.1906.11142,
title = {Strain-induced stripe phase in charge ordered single layer NbSe$_2$},
author = {Fabrizio Cossu and Krisztián Palotás and Sagar Sarkar and Igor Di Marco and Alireza Akbari},
journal= {arXiv preprint arXiv:1906.11142},
year = {2020}
}