<div dir="ltr">Hi Sebastian a gamma point calculation for Al metal using a model system consisting of only 3x3x3 unit cells won't provide converged results. You need a much larger model system in the order of 10x10x10 unit cells or you have to employ an equivalent k point sampling. Besides that major issue, there are further shortcomings in your CP2K input: (1) an SCF convergence threshold of 1.0E-4 (EPS_SCF) is too large: 1.0E-6 (or smaller), (2) a general threshold of 1.0E-10 (EPS_DEFAULT) is also too large: 1.0E-12 (or smaller) Best regards Matthias On Thursday, 1 June 2017 17:31:36 UTC+2, Sebastian Hütter wrote:<blockquote class="gmail_quote" style="margin:0;margin-left:0.8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hi all, this may be a simple question, but somehow I feel like I am missing something very basic here. I'm simply comparing bulk energies of metals (here: Al) computed over XYZ-periodic unit cells obtained via DFT in cp2k and several EAM potentials in LAMMPS. Different published potentials in LAMMPS all agree on an energy of somewhere around -14 eV/unit cell. However, when I run the same computation in cp2k (input file attached), I find energies (printed as the "FORCE_EVAL ( QS ) energy") of -8.3 Ha/unit cell, or -226 eV/unit cell. As this is more than one order of magnitude off, something can't be right here. To see if the relative energies are usable, I then tried to calculate vacancy formation energy by comparing the supercell energies with and without vacancies (cf. <a href="https://icme.hpc.msstate.edu/mediawiki/index.php/LAMMPS_Vacancy_Formation_Energy" rel="nofollow" target="_blank">https://icme.hpc.msstate.edu/mediawiki/index.php/LAMMPS_Vacancy_Formation_Energy</a>) , but that is wrong as well, while the LAMMPS solution agrees reasonably well with experimental data. It appears as if every energy value calculated is too large by a factor of 16? Why would that be the case? Thank your for your help, Sebastian </div></blockquote></div>