Dear Jakob, Do you mean the Helmoltz free energy (F)?
As by definition, the Gibbs free energy (G) does not depend upon volume, but on pressure and temperature. At p=0, then they are the same, but notice always that: G(p,T) = min_{V}[F(V, T)+pV] Thus, at p=0, you still need to take the minimum of F at the fixed temperature. Moreover, I guess you are using the quasi-harmonic approximation. There exist several flavours. Unless your system is isotropic, scaling the volume isotropically can be a source of error (due to a physical assumption, not due to the numerics). Best, Lorenzo Bastonero ******************************** Lorenzo Bastonero PhD Student U Bremen Excellence Chair, Bremen Center for Computational Materials Science, and MAPEX Center for Materials and Processes University of Bremen Faculty of Production Engineering TAB-Building, Room 3.32 Am Fallturm 1 28359 Bremen, DE http://www.hmi.uni-bremen.de/ > Il giorno 4 nov 2022, alle ore 09:20, Jakob Kraus > <jakob.kr...@physik.tu-freiberg.de> ha scritto: > > Dear QE users, > > > I am trying to calculate heat capacities, and to this end, I have calculated > the Gibbs energy as a function of volume > > at several temperatures in a range of 0-700 K. > > However, the functions that result from this do not show a single minimum, > but rather a whole lot of oscillations, which > > seem to originate from the phonons, since the E(V) diagram at 0 K shows a > single minimum as expected. > > I am thankful for any help you can offer with getting rid of these > oscillations. > > I have attached input files and some plots to showcase the problem. > > > Best regards, > > > Jakob Kraus, TU Freiberg > <G_Zr_BH4_0.0.png><E_Zr_BH4.png><espresso.qi><espresso.pwi><espresso.phi><espresso.mdi>_______________________________________________ > The Quantum ESPRESSO community stands by the Ukrainian > people and expresses its concerns about the devastating > effects that the Russian military offensive has on their > country and on the free and peaceful scientific, cultural, > and economic cooperation amongst peoples > _______________________________________________ > Quantum ESPRESSO is supported by MaX (www.max-centre.eu) > users mailing list users@lists.quantum-espresso.org > https://lists.quantum-espresso.org/mailman/listinfo/users
_______________________________________________ The Quantum ESPRESSO community stands by the Ukrainian people and expresses its concerns about the devastating effects that the Russian military offensive has on their country and on the free and peaceful scientific, cultural, and economic cooperation amongst peoples _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users