Hi Ben It would probably be helpful to see your input file, as there are many difficulties with iron and it could be any one of them!
What magnetism are you using? FCC iron is most stable in antiferromagnetic double layer spin state (unless you are willing to look into spin-spiral), and around the equilibrium volume there is a crossover in stability of the high-spin and low-spin ferromagnetic states and I've found it difficult to get convergence if you are off with the starting spin. I've found that mixing_beta = 0.1, with the default mixing scheme gives me the most efficient convergence, and increasing the number of k-points can sometimes help too. Tom Daff University of Cambridge -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Ben Palmer Sent: 28 June 2017 08:32 To: PWSCF Forum <[email protected]> Subject: [Pw_forum] End of SCF - convergence NOT achieved Hi Everyone, I'm trying to run a scf and vc-relax calculation for FCC Iron (nspin = 2). I've managed to do this for a 4 atom example (although the final scf calculation did fail: Error in routine ggen (138): smooth g-vectors missing !). When I scale up to 32 atoms, it fails to converge. I've increased the number of steps to 250, used Plain, TF and local-TF modes, changed the mixing mode, beta and ndim. I've also tried increasing nbnds and changing the starting magnetisation and celldm(1). The structure looks fine and I'm using the output from the 4 atom vc-relax calculation (scaled up 2x2x2). I wanted to ask if anyone has any suggestions on what I could try in order to get the calculation to converge? Thank you. Ben Palmer student @ University of Birmingham _______________________________________________ Pw_forum mailing list [email protected] http://pwscf.org/mailman/listinfo/pw_forum _______________________________________________ Pw_forum mailing list [email protected] http://pwscf.org/mailman/listinfo/pw_forum
