Formation energy and some mechanical properties of hydrogenated hexagonal monolayer of GeC

Mechanical properties of pristine and fully hydrogenated 2D hexagonal GeC monolayer were investigated by density functional theory calculations. Fully hydrogenated means that there is a hydrogen atom connected to each Ge and C atoms. Formation energy of fully hydrogenated GeC was negative which indicates that hydrogenated GeC is energetically stable. Uniaxial and biaxial strains were applied to the pristine and hydrogenated GeC in harmonic elastic deformation range and in-plane stiffness and Poisson's ratio were calculated by fitting the resulted strained energy to the strain-energy formula. Calculated in-plane stiffness and Poisson's ratio of hydrogenated GeC were respectively about 50% and 30% lower than those of pristine GeC. Pristine and hydrogenated GeCs are semiconductor and the band gap of hydrogenated GeC is larger than pristine. By Mulliken charge analysis we found that, in hydrogenated GeC, charge transfers from H atoms to GeC sheet.