What smearing would be ideal for a bcc W with interstitial O atom. I am running 3x3x3 unit cells with one N interstitial. I am having convergence issues in relaxrelax and vc-relaxvc-relax, but not in scfscf. Could this be due to smearing? I have tried mv and cold. For an additional interstitial atom, should we change or consider charge differences? There aren't many examples of interstitial atom studies other than papers which don't mentioned anything in particular about these.