It's nice to read that you got the desired results. Best,
Em 08.07.2018 00:30, Sunetra Das escreveu: > Dear Saif, > I followed your instructions and have been able to achieve the stable > configuration of my system. > Thank you very much. > > Regards, > Sunetra > > On 2 July 2018 at 20:41, Sunetra Das <sunetra.das...@gmail.com> wrote: > > Thank you very much for your kind help. > > On Mon 2 Jul, 2018, 1:32 AM sullah, <sul...@fisica.ufjf.br> wrote: > > Dear Sunetra, > > These links might be helpful. > > http://www.home.uni-osnabrueck.de/apostnik/Lectures/SIESTA-tuto.pdf [1] > > http://personales.unican.es/junqueraj/JavierJunquera_files/Metodos/Basis/Energy-Shift/Energy-Shift.pdf > [2] > > Best, > > Em 28.06.2018 17:38, Sunetra Das escreveu: > > Thank you Saif, I will use tighter force convergence like you said. > > Regarding the other three parameters, i.e. ElectronicTemperature , > PAO.EnergyShift , and PAO.SplitNorm, how do I test the convergence ? I did > not understand the basis set optimization from the tutorials. All I know is > that PAO.EnergyShift has to be some positive number and PAO.SplitNorm should > lie between the values 0.05 to 0.5, from the manual. Could you please tell me > what to do and how to check the optimum values for these parameters? > > Regards, Sunetra > > On 28 June 2018 at 21:33, sullah <sul...@fisica.ufjf.br> wrote: > > Dear Sunetra, > > It seems that the issue is due to the bad convergence criteria. Generally, > 1.d-6 is a good value for forces but for phonons, you may need 1.d-8 (you are > using DM.Tolerance 1.d-4). > > Furthermore, you are using (ElectronicTemperature 400 K, PAO.EnergyShift > 0.35 eV > PAO.SplitNorm 0.4), are you sure you need these values. Did you check the > convergence wrt the different values of these parameters ( especially the > EnergyShift and SplitNorm)? > > Best, > > Saif > > Em 27.06.2018 12:42, Sunetra Das escreveu: > > Hello Sullah, > > I have attached the input fdf file for your understanding of the possible > issue. > > Regards, Sunetra > > On 26 June 2018 at 02:53, sullah <sul...@fisica.ufjf.br> wrote: > > Dear Sunetra, > > It is difficult to say anything without taking a look at your input file(s). > How many negative frequencies do you have at gamma? What is (are) the > value(s) of the negative frequency(ies)? > > Anyways, this may be due to the bad convergence. I guess you are using the > DZP basis set which is sufficient in most of the cases. Try to increase the > value of mesh cutoff and keep a tight criterion for forces. > > I hope it helps. > > Best, > > Em 25.06.2018 01:31, Sunetra Das escreveu: > > Hello experts, > > I have been trying to optimize a 2D structure with 3 atoms in the unit cell. > I am using CG by varying the cell dimensions. I have optimized the k-points > and mesh cutoff. But no matter how many times I try to relax the structure, > it is giving a negative phonon frequency at the gamma point. The structure is > experimentally achieved structure with available .cif file. The cell > dimensions achieved after relaxation are the same as the experimentally > achieved one, with less than 2% deviation, and theoretical work publications > show that the structure should come out to a stable one with no negative > frequencies. > > Where can be the issue? I am using fully relativistic .psf files and > spin-polarization is on. Can basis set optimization be an issue? Help please. > > Regards, > Sunetra Das. Links: ------ [1] http://www.home.uni-osnabrueck.de/apostnik/Lectures/SIESTA-tuto.pdf [2] http://personales.unican.es/junqueraj/JavierJunquera_files/Metodos/Basis/Energy-Shift/Energy-Shift.pdf
