1.20 How do I calculate the isobaric heat capacity?

Use what='mur_lc_t' and the option lmurn=.TRUE.. This approach is rigorously valid only for cubic solids, for anisotropic solid it is an approximation in which only celldm(1) is changed while the other crystal parameters are kept constant. For the general case, see the elastic constants as a function of temperature. This calculation gives also the isobaric heat capacity as a function of temperature.