Phase stability and Raman vibration of the molybdenum ditelluride (MoTe₂) monolayer

The phase stability and phase transition of transition metal dichalcogenide (TMD) monolayer materials have attracted tremendous attention due to their attractive diverse potential applications. Here, first-principles calculations based on density-functional theory are carried out to study the newly synthesized MoTe₂ monolayer. A phase different from the semiconducting trigonal prismatic structure and octahedral coordinated structure is found to be stable at room temperature in a free standing state, as evidenced by phonon spectrum analysis and molecular dynamic simulation. Raman vibrations of all the possible phases are calculated to provide additional information for the distinction of different phases in the experiment.