Hi Stefano and Giuseppe, Thanks for your feedback.
I just wanted to try 48 atom supercell initially and see how it goes (to save computation time as well). I will try 108 atom supercell definitely. Is EXX-ACE implemented in QE 6.1v by default or do I have to compile it separately?. I will try to run it (if our busy HPC facility permits!). If I am not using HSE , do I have to use LDA level theory for TiO2 with defects?. Thanks Manu (University of Waterloo) On Sun, Aug 6, 2017 at 6:08 PM, Giuseppe Mattioli < [email protected]> wrote: > > On the top of Stefano's answer, I would add that in a 48 atom > supercell the interaction between the relaxation sphere of an oxygen > vacancy and its periodic images along the 100 or 010 directions is too > strong and can lead to an improper description of the electronic > properties of the defect that can not be considered as an "isolated > defect" anymore. I suggest that you use at least a 3x3x1 108-atom > supercell. With the new EXX-ACE implementation you may probably afford > an HSE calculation, otherwise remember also that the small-polaron > character of excess electrons in TiO2 such as those induced by the O > vacancy is not at all well described at the GGA level of theory. > HTH > Giuseppe > > stefano de gironcoli <[email protected]> ha scritto: > > > yes > > start from the perfect relaxed geometry (as obtained from vc-relax) > > remove an atom and relax the internal structure. > > at the end also perform a vc-relaxation (from the fixed-cell relaxed > > geometry) > > stefano > > > > On 06/08/2017 17:33, Manu Hegde wrote: > >> Hello Stephano, > >> Thanks for your reply. Just to double check what you meant before > >> starting the calculations, you mean take the equilibrium values > >> from the vc-relax calculation (perfect cell, only co-ordinates) > >> and do the 'relax' calculation with defect?. > >> Manu > >> (University of Waterloo). > >> > >> > >> On Sun, Aug 6, 2017 at 11:15 AM, stefano de gironcoli > >> <[email protected] <mailto:[email protected]>> wrote: > >> > >> does the energy (enthalpy) decreases as the vc-relaxation > >> progresses ? > >> The local structure around the defect may be quite different. It > >> may just take long. > >> > >> I would start by performing a fixed cell relaxation with the cell > >> parameters fixed at the undefected equilibrium values. And only > >> after that I would start the vc-relax calculation from the so > >> relaxed configuration to evaluate the vacancy formation volume. > >> The local arrangement around the defect should be already more or > >> less ok (if the supercell is large enough). > >> > >> HTH > >> stefano > >> > >> > >> > >> On 06/08/2017 16:40, Manu Hegde wrote: > >>> Hello, > >>> > >>> I am trying to optimize anatase TiO2 supercell with 48 atoms. The > >>> supercell converges in 15 BFGS cycles for a perfect cell. But > >>> when I introduce defect (by removing one of the oxygen atom), the > >>> vc-relax is not t all converging. I am using the same parameters > >>> in both the cases. Can anyone give some feedback on this.?. Here > >>> is my input, > >>> > >>> > >>> &control > >>> calculation = 'vc-relax' , > >>> restart_mode = 'from_scratch' , > >>> outdir = '/work/mhegde/tmp_tiodef/', > >>> pseudo_dir = '/home/mhegde/tio_project/def_tio/', > >>> prefix = 'tioan', > >>> verbosity = 'high', > >>> > >>> / > >>> &system > >>> ibrav = 0, > >>> nat = 47, > >>> ntyp = 2, > >>> ecutwfc =40, > >>> ecutrho=400, > >>> occupations='smearing', > >>> degauss=0.003 > >>> > >>> / > >>> &electrons > >>> conv_thr = 1.D-6, > >>> mixing_beta=0.1 > >>> / > >>> &ions > >>> ion_dynamics='bfgs' > >>> > >>> / > >>> &cell > >>> cell_dynamics='bfgs' > >>> > >>> / > >>> ATOMIC_SPECIES > >>> Ti 47.867000 Ti.pw91-nsp-van.UPF > >>> O 15.99900 O.pw91-van_ak.UPF > >>> > >>> ATOMIC_POSITIONS angstrom > >>> Ti 0.00000000 2.84182500 1.20970000 > >>> Ti 1.89455000 2.84182500 3.62910000 > >>> O 0.00000000 0.94727500 1.99939216 > >>> O 0.00000000 2.84182500 4.41879216 > >>> O 1.89455000 0.94727500 2.83940784 > >>> Ti -1.89455000 0.94727500 -3.62910000 > >>> Ti 0.00000000 0.94727500 -1.20970000 > >>> O -1.89455000 -0.94727500 -2.83940784 > >>> O -1.89455000 0.94727500 -0.42000784 > >>> O 0.00000000 -0.94727500 -1.99939216 > >>> O 0.00000000 0.94727500 -4.41879216 > >>> Ti 0.00000000 -0.94727500 1.20970000 > >>> Ti 1.89455000 -0.94727500 3.62910000 > >>> O 0.00000000 -2.84182500 1.99939216 > >>> O 0.00000000 -0.94727500 4.41879216 > >>> O 1.89455000 -2.84182500 2.83940784 > >>> O 1.89455000 -0.94727500 0.42000784 > >>> Ti -1.89455000 -2.84182500 -3.62910000 > >>> Ti 0.00000000 -2.84182500 -1.20970000 > >>> O -1.89455000 2.84182500 -2.83940784 > >>> O -1.89455000 -2.84182500 -0.42000784 > >>> O 0.00000000 2.84182500 -1.99939216 > >>> O 0.00000000 -2.84182500 -4.41879216 > >>> Ti -3.78910000 2.84182500 1.20970000 > >>> Ti -1.89455000 2.84182500 3.62910000 > >>> O -3.78910000 0.94727500 1.99939216 > >>> O -3.78910000 2.84182500 4.41879216 > >>> O -1.89455000 0.94727500 2.83940784 > >>> O -1.89455000 2.84182500 0.42000784 > >>> Ti 1.89455000 0.94727500 -3.62910000 > >>> Ti -3.78910000 0.94727500 -1.20970000 > >>> O 1.89455000 -0.94727500 -2.83940784 > >>> O 1.89455000 0.94727500 -0.42000784 > >>> O -3.78910000 -0.94727500 -1.99939216 > >>> O -3.78910000 0.94727500 -4.41879216 > >>> Ti -3.78910000 -0.94727500 1.20970000 > >>> Ti -1.89455000 -0.94727500 3.62910000 > >>> O -3.78910000 -2.84182500 1.99939216 > >>> O -3.78910000 -0.94727500 4.41879216 > >>> O -1.89455000 -2.84182500 2.83940784 > >>> O -1.89455000 -0.94727500 0.42000784 > >>> Ti 1.89455000 -2.84182500 -3.62910000 > >>> Ti -3.78910000 -2.84182500 -1.20970000 > >>> O 1.89455000 2.84182500 -2.83940784 > >>> O 1.89455000 -2.84182500 -0.42000784 > >>> O -3.78910000 2.84182500 -1.99939216 > >>> O -3.78910000 -2.84182500 -4.41879216 > >>> > >>> K_POINTS {automatic} > >>> > >>> 2 2 2 0 0 0 > >>> > >>> CELL_PARAMETERS angstrom > >>> > >>> 7.57820000 0.00000000 0.00000000 > >>> 0.00000000 7.57820000 0.00000000 > >>> 0.00000000 0.00000000 9.67760000 > >>> > >>> Thanks, > >>> Manu > >>> (University of Waterloo) > >>> > >>> > >>> > >>> > >>> > >>> > >>> _______________________________________________ > >>> Pw_forum mailing list > >>> [email protected] <mailto:[email protected]> > >>> http://pwscf.org/mailman/listinfo/pw_forum > >>> <http://pwscf.org/mailman/listinfo/pw_forum> > >> > >> > >> > >> _______________________________________________ > >> Pw_forum mailing list > >> [email protected] <mailto:[email protected]> > >> http://pwscf.org/mailman/listinfo/pw_forum > >> <http://pwscf.org/mailman/listinfo/pw_forum> > >> > >> > >> > >> > >> _______________________________________________ > >> Pw_forum mailing list > >> [email protected] > >> http://pwscf.org/mailman/listinfo/pw_forum > > > -- > ******************************************************** > - Article premier - Les hommes naissent et demeurent > libres et égaux en droits. Les distinctions sociales > ne peuvent être fondées que sur l'utilité commune > - Article 2 - Le but de toute association politique > est la conservation des droits naturels et > imprescriptibles de l'homme. Ces droits sont la liberté, > la propriété, la sûreté et la résistance à l'oppression. > ******************************************************** > > Giuseppe Mattioli > CNR - ISTITUTO DI STRUTTURA DELLA MATERIA > v. Salaria Km 29,300 - C.P. 10 > I 00015 - Monterotondo Stazione (RM) > Tel + 39 06 90672836 - Fax +39 06 90672316 > E-mail: <[email protected]> > http://www.ism.cnr.it/en/staff/giuseppe-mattioli/ > ResearcherID: F-6308-2012 > > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum >
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