Thanks for your response Prof. Artacho! So if I have a situation like below for a large metallic system in which FreeEng is lower than Etot, should I use Etot? Specifically, if I want to plot the E-V curve from single point runs to obtain the equation of state I should use Etot instead of FreeEng? Or if I want to compute the cohesive energy, Etot should be used instead of FreeEng?
siesta: Program's energy decomposition (eV): siesta: Ebs = -859.157108 siesta: Eions = 9568.777238 siesta: Ena = 277.651800 siesta: Ekin = 4247.415878 siesta: Enl = -1698.956164 siesta: Eso = 0.000000 siesta: Edftu = 0.000000 siesta: DEna = 162.636813 siesta: DUscf = 26.981770 siesta: DUext = 0.000000 siesta: Exc = -6715.533109 siesta: eta*DQ = 0.000000 siesta: Emadel = 0.000000 siesta: Emeta = 0.000000 siesta: Emolmec = 0.000000 siesta: Ekinion = 0.000000 siesta: Eharris = -13268.580292 siesta: Etot = -13268.580250 siesta: FreeEng = -13269.911499 On Tue, Jun 21, 2022 at 2:07 PM Emilio Artacho <e.arta...@nanogune.eu> wrote: > > On 20 Jun 2022, at 17:16, Francisco Garcia <garcia.ff....@gmail.com> > wrote: > > Dear users, > > In metallic systems with a fairly sizable electronic smearing temperature > T, is it accurate to claim that > > (i) in a single point calculation, the free energy is the representative > energy of the system (due to the addition of -TS to the total energy U) > > > No, the -TS term for the phononic entropy is missing. > > It is the free energy defining the finite temperature equilibrium for the > purely electronic > problem for fixed external potential (fixed nuclei), as in Mermin’s finite > -T DFT. > > > (ii) in a variable cell optimization, the enthalpy is the representative > energy of the system (due to the addition of the PV term to the energy). > > > Yes, it is the free energy of the system (minimum defines equilibrium) for > T=0. > > Emilio > > > Thanks! > > > -- > SIESTA is supported by the Spanish Research Agency (AEI) and by the > European H2020 MaX Centre of Excellence (http://www.max-centre.eu/) > > > -- > Emilio Artacho > > Theory Group, Nanogune, 20018 San Sebastian, Spain, and > Theory of Condensed Matter, Department of Physics, > Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK > > > > > > -- > SIESTA is supported by the Spanish Research Agency (AEI) and by the > European H2020 MaX Centre of Excellence (http://www.max-centre.eu/) >
-- SIESTA is supported by the Spanish Research Agency (AEI) and by the European H2020 MaX Centre of Excellence (http://www.max-centre.eu/)
