▎ 摘　　要

The investigation assesses the thermal-mechanical and thermodynamic properties of various graphene sheets using a modified Nose-Hoover (NH) thermostat method incorporated with molecular dynamics (MD) simulation. The investigation begins with an exploration of their thermal-mechanical properties at atmospheric pressure, including Young's modulus, shear modulus, Poisson's ratio, specific heats and linear and volumetric coefficients of thermal expansion (CTE). Two definitions of the line change ratio (Delta L/L) are utilized to determine the linear CTE of graphene sheets, and the calculations are compared with each other and data in the literature. To estimate the volumetric CTE values, the Connolly surface method is applied to predict the volume of the deformed graphene sheets in the free relaxation state and under temperature loading. Their specific heats are also determined by estimating the ratio of the amount of heat energy per unit mass that is required to raise the temperature-by one degree. Finally, the dependences of the size and temperature on the thermal-mechanical and thermodynamic properties are examined. The calculations are validated by comparison with the results obtained from the existing thermostats and with the literature experimental and theoretical data The results indicate that the presently calculated thermal-mechanical and thermodynamic properties of graphene sheets are very similar to the published experimental and theoretical results. The graphene sheets tend to have a negative linear CTE at temperatures below 300 K. Additionally, the calculated linear CTE of graphene sheets depends strongly on the line-change-ratio assumptions. The modified NH thermostat is the only one of five thermostats that can accurately reproduce the Debye T-3-dependent specific heat at temperatures below the Debye temperature.