Thanks a lot Nick! 2017-06-21 7:10 GMT-03:00 Nick Papior <[email protected]>:
> There is not much to do other than trial an error. > > Typically one can get a better convergence by increasing the number of > layers that separate the junction and the electrodes. I.e. if the > electrostatics are long-range. > Also, when you have vacuum regions as terminations of the buffer layers > you could also increase the number of layers "behind" the electrode to > better screen the surface. > > Other than that it is difficult, it is purely trial and error. > > You could try with siesta-4.1-b2 which has better convergence, and is > _much_ faster than the previous versions of transiesta. > 4.1 also enables one to fix the DM in the electrodes to match that of the > pristine electrode (see flag: TS.Elecs.DM.Init). This _may_ improve a bit > the convergence. > > 2017-06-20 14:31 GMT+02:00 Leonardo Fonseca <[email protected]>: > >> 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? >> > > > > -- > Kind regards Nick >
