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]> 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 > [email protected]http://pwscf.org/mailman/listinfo/pw_forum > > > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum >
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