Hello I am trying to relax a system with unit cell made of 24 silicon atoms and 2 talium atoms, one in each edge. I wish the system to be a surface, so the unit cell has vacuum between the talium atoms so that they do not "see" each other. I tried to relax it following the Example03 of Quantum Espresso which is a surface of "al001". In the example there are two methods, I followed the first one, the one of the "bfgs" method. When I use Scalar_Relativistic pseudopotentials (for both atoms) it is Ok, after some trials the system relaxes. However, when I use Relativistic pseudopotentials (for both atoms) the system cannot relax, after many trials the system repeats the atomic configuration and stops. I have tried both, to let all the atoms move and to let move just a few of the surface, keeping the other fixed, but it does not work anyway. The most I can get is that the force in every atom is smaller than 0.01Ry/au. Both pseudopotentials work allright in simpler models. I would appreciate any suggestion. Thank you very much
Julen UPV/EHU, Fisica de la Matertia Condensada -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20100204/57c4cdcb/attachment.htm
