Dear Sergi Vela, are you really sure about input coordinates? I executed "xcrysden --pwi Test.input" and found a rather strange structure!
Also, do you really need to use ibrav=0 with the axes as you defined? It the substrate is Au(111) you could use a more symmetric unit cell. Then: k-point mesh seems to me too coarse (if that was not intentional for testing) HTH Guido On 03/02/2015 10:57, Sergi Vela wrote: > Hi all, > > I'm having a lot of troubles in modeling the adsorption of molecules on > surfaces. I've quite a lot of experience with QE when working with > crystals made of open-shell molecules but I'm not familiar with the > description of metal surfaces. > > First of all, I'm using Qespresso v.5.1.1 > > I succeed in simulating 4 layers of a 111 Gold surface with Quantum > Espresso (QE). However, using the same surface and unit cell, when I > include a magnetic (open-shell) molecule on top of that surface, even if > its far away from it, I cannot reach convergence. I'm 99% sure that the > input is fine in terms of the unit cell definition (see input file > attached) and the problem is just the convergence of the electronic > structure. > > I believe the problem is the fact that the system is highly > inhomogeneous as it has a metal surface and an open-shell molecule. I > take as an example the smearing, since, although it is mandatory when > modeling the metal alone, it seems to hinder the description of an > open-shell molecule. Originally, I used methfessel-paxton smearing with > a 'degauss' of 0.2 eV. The convergence seems to be even worse as the > value is increased, and changing the type of smearing doesn't help neither. > > I've tried several tricks to try to improve electronic structure's > convergence. Changing the 'mixing_beta', the 'type of mixing', removing > the smearing, switching to 'cg' algorith, increasing number K points ... > all of them with identical output (take Summary.out as an example of the > typical evolution of the SCF energy, you'll see that is awful). > > Anyone has experience on modeling such king of systems? > > Any help is appreciated, thanks in advance > > Dr. Sergi Vela, > University of Strasbourg, France. > > -- Guido Fratesi Dipartimento di Fisica Universita` degli Studi di Milano Via Celoria 16, 20133 Milano, Italy _______________________________________________ Pw_forum mailing list [email protected] http://pwscf.org/mailman/listinfo/pw_forum
