Thermodynamics of H-T phase transition in MoS$_2$ single layer

Molybdenum disulfide is a title compound among the layered metal dichalcogenides, being a prominent tribological agent and vital platform for catalysts. The properties of a MoS$_{2}$ layer can vary widely, depending upon polymorphic composition. Here, using the density-functional theory calculations, the potential energy surfaces for polymorphic H- and T-MoS$_{2}$ layers are mapped. While the energy barriers for H$\to$T and T(T')$\to$H transitions are found to be in fair agreement with previous studies which employed the nudged elastic band method, the bird’s-eye view at the energy landscape of MoS$_{2}$ layer has disclosed the as-yet undescribed energy plateau attributed to an intermediate - square lattice of MoS$_{2}$ layer (S-MoS$_{2}$). The stability, structural and electronic properties of S-MoS$_{2}$ are discussed in comparison with those for H- and T-MoS$_{2}$ layers.