Calculation of mechanical properties of solids using molecular dynamics method

We describe the calculation of mechanical properties of solids using the molecular dynamics method. The thermal expansion coefficient and elastic constants of α-Fe are calculated using an empirical potential, that is, the Johnson potential. The thermal expansion coefficient is calculated using a differential operation of the temperature dependence of the lattice constant obtained from the NPT ensemble molecular dynamics analysis. Reasonable agreement is found between the analytical results and measured data up to the phase transition temperature. The elastic constants are calculated from the stress-strain curves obtained from the NVT ensemble, the initial lattice constant of which is modified based on the result of the NPT ensemble. The analytical results agree reasonably well with the measured data up to 400 K.