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 >> >> 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 <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. >>>> >>>> >>>> >>> >>
