I want to incorporate the temperature effect on elastic constant (EC) of a system using VASP.
From literature, there are two ways which can be used to get the temperature effect on EC i) ab initio molecular dynamics ii) standard DFT with quasi harmonic approximation (as far as I know). Based on the second approach, standard DFT calculation with IBRION = 5 or 6 with ISIF = 3 tags can generate EC at 0 Kelvin for a particular volume. Again, volume vs. temperature data is one of the outputs of the phonon codes (QHA). But somehow I am not able to correlate this two quantities.
Can somebody please explain a detailed way for getting the temperature effect by considering both theories and code (VASP)?