Dear Dr. Stefano and Dr. Nicola Marzari thanks for your quick reply. Actualy i have calculated the Helmholtz free energy (F) which is given as
F(V, T) = E0(V) + Fvib (V, T). The Fvib(V, T) is calculated by PH/fqha.x utility and E0(V) is the equilibrium ground state energy which is calculated by pw.x. it is stated in a research paper>>>>For a given T and V, the equilibrium state of the crystal is determined by minimising F with respect to all possible degrees of freedom. The equation of state (pressure (P) versus V) of the system is obtained by equating P to minus the derivative of F with respect to V at constant T, or P = ? (?F/?V)T <<<<<< Sir i was tried for QHA package in QE as given paper http://arxiv.org/abs/1112.4977v1 , it is using the QHA pakage which is not well understood by me and also this was giving wrong result but it was ok with PH/fqha.x. Please show me the ray of light regarding Helmholtz free energy (F) which is the base root of all thermodynamics property describe by one paper http://iopscience.iop.org/0953-8984/24/3/035401 for your kind reference. Any comment in any form is appreciable. 2012/3/24 Nicola Marzari <nicola.marzari at epfl.ch> > > Here it is: > > http://arxiv.org/abs/1112.**4977v1 <http://arxiv.org/abs/1112.4977v1> > Thermal properties of materials from ab-initio quasi-harmonic phonons > Stefano Baroni, Paolo Giannozzi, Eyvaz Isaev > > nicola > > > > On 24/03/2012 05:35, bramha pandey wrote: > >> Dear All, >> I want to incorporate the temperature effect in my calculation. As i >> know for this purpose firstly i have to compute the free energy and then >> this free energy is added to the ground state total energy(T=0,P=0). >> then by the equation of state we have to find out the lattice parameter. >> But i am wonder if i am trying to fit eos, it will give the equilibrium >> lattice parameter not the temperature dependent lattice parameter. >> Please let me know whether i am proceeding wrong way if so then how can >> i obtained my lattice parameter which is dependent upon temperature? >> Any type of help is highly appreciable . >> >> -- >> Thanks and Regards >> Bramha Prasad Pandey >> GLA University, Mathura. >> INDIA. >> >> >> >> ______________________________**_________________ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/**mailman/listinfo/pw_forum<http://www.democritos.it/mailman/listinfo/pw_forum> >> > > > -- > > ------------------------------**------------------------------**---------- > Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL > -- Thanks and Regards Bramha Prasad Pandey GLA University, Mathura. INDIA. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20120325/535c17f4/attachment.htm