Dear Apsi, and Francesco Thank you very much for your prompt answer. I have already try to increase the energy cutoff and I saw a very reasonable change (about 0.1 bohr) . I will try later also the Free energy functionals too. best regards Imre Bakó Imre MTA Kémiai Kutatóközpont, Kémiai Intézet 1525 Budapest Pf. 17 Telefon