Dear all, I have been converging transiesta 4.0 without problems for a
number of systems, including graphene and gold chains. However, I recently
tried to calculate the transmission function for Ti/HfO2/TiN and could not
make it converge. The DM part converges fine, but the GF part oscillates. I
tried longer buffer regions, more k-points and smaller mixing parameters
(0.0002 right now), to no avail. Then I replaced TiN by Ti to simplify the
problem. With that change the size of the system decreased from 258 to 120,
by eliminating vacuum along z and and the necessary buffer layers. The GF
part also oscillates. Finally, I also noticed that upon restarting the job
in the GF part in case it has not converged, the progress obtained in the
previous job is totally lost, and major oscillations in the total energy
take place for several steps. Any ideas on how to improve the convergence
in situations like this?
