Temperature dependence of thermodynamic properties of MoS monolayer and single-wall nanotubes: Application of the developed three-body force field.

MoS nanostructures, especially mono-, multilayer nanothin films as well as single- and multiwall nanotubes are rather interesting popular objects in nanomaterials chemistry. The thermodynamic properties of inorganic nanotubes, and the temperature dependence of their properties can be efficiently investigated by first-principles and molecular mechanics methods in the framework of harmonic approximation. At the same time, only thin single-wall nanotubes are available for the first-principles calculations. The classical mechanics is suitable to simulate very large atomic systems and their phonon frequencies, but developing sufficiently accurate force field is rather tedious work. Herein, we report the force field fitted to the experimental and first-principles data on the structure of 2H- and 3RMoS polytypes of bulk crystal, structure of monolayer and several bilayers, vibrational frequencies of 2HMoS bulk and monolayer, relative energetic stability of polytypes experimental and first-principles data, elastic constants, strain energy of a (12, 12) MoS nanotube. The thermodynamic functions and their temperature dependence for the armchair and zigzag nanotubes are calculated within the formalism of molecular mechanics using elaborated interatomic potential. The results of molecular mechanics and first-principles method application to the thinnest nanotubes are compared.