Thank you Dr. Tran Yes, I took only 6x6x6 k-mesh for optimization. I will test it further for 8x8x8, 10x10x10
On Fri, May 5, 2017 at 1:00 AM, <t...@theochem.tuwien.ac.at> wrote: > Hi, > If the SCF calculations were done with a value for a parameter (e.g., > RKmax, number of k-points or energy convergence criteria) that was > not good enough, then this may introduce some noise such that the > Murnaghan EOS can not fit perfectly the data and, therefore, > leads to an optimised lattice parameter that depends on the chosen > volumes to do the fit. > > In your case the fit does not seem perfect, but still reasonable > since the variations in the lattice parameter are only at the > third digit (at most tiny changes in the electronic properties). > > FT > > On Thursday 2017-05-04 20:34, fatima DFT wrote: > > Date: Thu, 4 May 2017 20:34:34 >> From: fatima DFT <fatimad...@gmail.com> >> Reply-To: A Mailing list for WIEN2k users <w...@zeus.theochem.tuwien.ac. >> at> >> To: A Mailing list for WIEN2k users <Wien@zeus.theochem.tuwien.ac.at> >> Subject: [Wien] optimization for 225 (cubic) space group >> >> Dear All,I finished an optimisation for 225 space group with -15% to 25% >> volume change. >> >> If I plot the optimization cure for different vol parameters, I see the >> shape of ENE vs. Vol curve changes and the optimised lattice parametes also >> changes (at >> third digit). >> >> If I plot the curve for -15 to 25% then I get the below curve >> https://sites.google.com/site/dftfatima5/letter/mailing-list-queries/1.ps >> >> >> and the optimised lattice parameters are >> >> 21.1924 bohr = 11.2145 Ang >> >> For -10 to 25%, >> https://sites.google.com/site/dftfatima5/letter/mailing-list-queries/2.ps >> >> 21.1984 bohr = 11.2177 Ang >> >> For -5 to 25% >> https://sites.google.com/site/dftfatima5/letter/mailing-list-queries/3.ps >> >> 21.1915 bohr = 11.2140 Ang >> >> 0.0 to 25 % >> https://sites.google.com/site/dftfatima5/letter/mailing-list-queries/4.ps >> >> 21.1917 bohr = 11.2141 Ang >> for 5.0 to 25 % >> https://sites.google.com/site/dftfatima5/letter/mailing-list-queries/5.ps >> 21.2026 bohr = 11.2199 Ang >> >> >> My query is: >> >> 1. Why the optimised lattice parameters are changing if we select >> different set of data points? The ground state should be same in all cases. >> Is it? >> 2. We see from the lattice parameter the change is at third order, can >> we take any lattice parameters (a0)? How much the third digit changes the >> electronic >> properties? >> >> >> Warm regards >> Fatima >> >> >> > _______________________________________________ > Wien mailing list > Wien@zeus.theochem.tuwien.ac.at > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > SEARCH the MAILING-LIST at: http://www.mail-archive.com/ > wien@zeus.theochem.tuwien.ac.at/index.html > >
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