Dear users, I'm trying to obtain the properties of the crystal of a drug (ibrav = -12). At the beginning of this work, I was using the ONCV NC PPs from the SG15 database and PseudoDojo (PBE), but both PPs gave me lattice parameters shorter than the crystal values, after optimization. These values were <2% shorter, but most of the literature shows that GGA functionals give lattice parameters longer than experimental ones. So, I changed to the US PPs downloaded from the QE website (also PBE), and most of the values obtained after VC-relax were longer (<1%) than the experimental (as I expected from the literature).
Since I want to perform calculations to get the optical and vibrational properties of the crystal, I should use the NC PPs. However, I'm afraid it could give me the wrong vibrational/optical results. So, I would like to make some questions. 1- The input file was the same, So what could be the reason for that (small) difference? 2- Despite the small difference between ONCV NC PPs and US PPs for my lattice parameters, continuing using the first PP could give me a wrong result in the next calculations? 3- Is it "wrong" to use the USPPs to perform the vc-relax calculation and the ONCVNC for the other calculations? 4- Are there other ways to perform optical/vibrational/thermodynamic calculations by using the USPP or PAW PPs? I read superficially about BoltzTrap, but I don't know if it is possible. Thanks for your time and help. Sincerelly, José Xavier UFRN - Brazil _______________________________________________ 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 [email protected] https://lists.quantum-espresso.org/mailman/listinfo/users
