> Dear all, > > I intend to calculate the exchange integral of CdFe2O4, so I need the > energy > of four magnetic structures, one ferromagnetism and three > antiferromagnetism. The ferromagnetic system have finished in 40 hours, > but > the antiferromagnetic system have taken about 170 hours. The calculation > converged so slowly and there was already 700 interations.
Hi, it is normal that as you increase your system to include many equivalent (or almost) atoms, the convergence becomes difficult, because of electrons flopping between nearly degenerate states. So sometimes you need just patience and very small mixnig parameter. The crucial question is, is your calculation on the right way and simply converges slowly, or is it wildly fluctuating. To get an idea, look at the results (Mulliken charges; DOS) underway, after some number of iterations. Good luck Andrei Postnikov
