Thank you very much for your kind help.
On Mon 2 Jul, 2018, 1:32 AM sullah, <[email protected]> wrote: > Dear Sunetra, > > These links might be helpful. > > http://www.home.uni-osnabrueck.de/apostnik/Lectures/SIESTA-tuto.pdf > > > http://personales.unican.es/junqueraj/JavierJunquera_files/Metodos/Basis/Energy-Shift/Energy-Shift.pdf > > 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 <[email protected]> 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 <[email protected]> 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. >>> >>> >>> >> >
