First principles investigation of the finite temperature dependence of the elastic constants of zirconium, magnesium and gold

• Temperature dependent elastic properties of metals are studied using DFT.
• Helmholtz free strain energy is calculated using the quasi-harmonic approximation.
• For Zr it is found that the adiabatic C12 and C13 increase with increasing temperature.
• For Mg and Au the calculated elastic properties concur well with experimental data.

The purpose of this work is to investigate how well the temperature dependence of the elastic constants of single crystal zirconium, magnesium and gold are reproduced by ab initio   density functional theory (DFT). The modelling was conducted via the quasi-harmonic approximation with the exchange–correlation functional based on the local density approximation. For gold and magnesium, the low and high temperature dependency agrees well with measurements, whereas the transition between low and high temperature ranges occurs over a wider range of temperature than observed experimentally. For zirconium, the simulations qualitatively predict the temperature dependence of the isentropic elastic constants, where C12C12 and C13C13 increase with increasing temperature. Because this behaviour is absent for the isothermal elastic constants, the increase can be attributed to the transformation from isothermal to isentropic elastic constants.

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