Dear Adetunji,
> How can i calculate the elastic constants(C11,C12 and C44) at (0 K) and > (0 GPa) of a semiconductor compound using pwscf ?. by taking the second derivative of the energy with respect to the appropriate strain - it would be good to look at a book on elasticity (e.g. Kittel) to clarify these concepts, and the Voigt notation (these are 4th rank tensors, connecting strain and stress, but in a cubic material e.g. C12=Cxxxy) > The second question: > In studying the phase transition, we need to analysed the enthalpy > variation with pressure. Where the enthalpy(H) = E + PV. So, how can > this be implemented using pwscf? > These are my questions. You calculate E as a function of V, and for every calculation you get P from the trace of the stress tensor, and construct H. nicola -- ---------------------------------------------------------------------- Prof Nicola Marzari Department of Materials University of Oxford Chair of Materials Modelling Director, Materials Modelling Laboratory nicola.marzari at materials.ox.ac.uk http://mml.materials.ox.ac.uk/NM