Hello Sebastian, I have had similar problems with convergence of the scf cycle. They were solved when I changed from Pulay mixing to Broyden mixing for the charge density.
Usually if something doesn't converge in 250 cycles, it probably never will. Also you can play with the DM.Tolerance. For very difficult systems I set it to 0.0008 and then restart from that DM file with a stringer convergence criterion. Here is the settings I am using for my calculations: #--------------------Convergence of SCF------------------------------- MeshCutoff 200.0 Ry # Default value PW cutoff for grid MaxSCFIterations 250 # Maximum number of SCF iter DM.NumberBroyden 3 DM.MixingWeight 0.01 # New DM amount for next SCF cycle DM.Tolerance 0.0001 # Tolerance in maximum difference DM.UseSaveDM .false. # to use continuation files DM.NumberKick 100 DM.KickMixingWeight 0.01 #---------------------------------- Suerte! PS: yo tambien soy caleña! Diana M. Otálvaro PhD Candidate Computational Material Science MESA+ Institute of Nanotechnology University of Twente. Enschede, Nederland ________________________________ From: [email protected] [[email protected]] on behalf of Максим Арсентьев [[email protected]] Sent: Wednesday, November 20, 2013 7:29 AM To: [email protected] Subject: Re: [SIESTA-L] Convergence problem on heterostructure. I forgot to tell you - besides DM.MixingWeight 0.05 I also set PAO.EnergyShift to 65 meV as here http://www.nature.com/nnano/journal/v7/n9/extref/nnano.2012.127-s2.txt . Best wishes, Dr. Maxim Arsent'ev Laboratory of inorganic synthesis Institute of Silicate Chemistry of RAS 2013/11/18 Mahmoud Hammouri <[email protected]<mailto:[email protected]>> You could also try to increase the non-equilibrium contour points. Mahmoud On Nov 18, 2013, at 11:22, "Sebastián Cauce do Dávila" <[email protected]<mailto:[email protected]>> wrote: Thank you very much for your suggestion. I will give it a try! Sebastián Caicedo Dávila Bionanoelectronics research group School of electrical and electronics engineering Universidad del Valle Cali - Colombia On 18/11/2013, at 11:50, Максим Арсентьев <[email protected]<mailto:[email protected]>> wrote: I also try some siesta only six months, but for a more heterogeneous structure I noticed that the reduction DM.MixingWeight reduces oscillations in convergence, so try to play with it (decrease DM.MixingWeight). See http://www.nature.com/nnano/journal/v7/n9/extref/nnano.2012.127-s2.txt Maybe someone will tell something else. 2013/11/18 Sebastian Caicedo D. <[email protected]<mailto:[email protected]>> Dear Siesta/Transiesta users, I've been using the software for a couple months and made some calculations of InAs and InP unit cell quite successfully. Now I intend to work on transiesta calculations of a heterostructure of both these materials (InAs bulk with InP barriers). As a first approach I want to simulate a couple of InAs unit cells and the barriers shall be unit cells of InP, just to get a qualitative idea. The electrodes .TSHS files were obtained from the previous calculations of the InAs unit cell. I wanted first to run a siesta calculation of the whole heterostructure, so I can take a look at the eigenvalues and define a correct value for the parameter TS.ComplexContour.Emin, as suggested in the manual. The structure has 120 atoms and I'm using LDA Pseudopotentials, obtained from the siesta webpage. (In Pseudo includes semicore electrons, so we have enough electrons to build a zinc-blende structure). The issue is that after 1000 SCF steps, the energy doesn't converge at all. I'm doing a Gamma-point calculation, but even when I make the k-grid 1x1x15 it doesn't work either. I used the same MeshCutoff as for the individual materials unit cell an 200Ry and I increased the Energy Shift, so the calculation would be a bit faster though less precise. I attach the Input (INPUT.fdf, STRUCTURE.fdf) and output files. I would really appreciate any suggestions. sincerely Sebastian Caicedo Davila Bionanoelectronics Group School of Electrical and Electronics Engineering Universidad del Valle Cali-Colombia -- Best wishes, Dr. Maxim Arsent'ev Laboratory of inorganic synthesis Institute of Silicate Chemistry of RAS -- Best wishes, Dr. Maxim Arsent'ev Laboratory of inorganic synthesis Institute of Silicate Chemistry of RAS
