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. >> >> >> >
