[Pw_forum] vc-relax convergence
Manu Hegde
mhegde at uwaterloo.ca
Mon Aug 7 17:07:41 CEST 2017
Dear Giuseppe,
Thank you very much!
Manu
On Mon, Aug 7, 2017 at 7:18 AM, Giuseppe Mattioli <
giuseppe.mattioli at ism.cnr.it> wrote:
>
> Dear Manu
>
> > Is EXX-ACE implemented in QE 6.1v by default or do I have to compile it
> > separately?.
>
> Honestly, I would not give it for granted! Put the ACE flag in the
> make.inc file, it should not harm. :-)
>
> > If I am not using HSE , do I have to use LDA level theory for TiO2 with
> > defects?.
>
> Note that there are tons of papers on TiO2 defects. If you do not want
> to use EXX, then you can try with DFT+U(Ti,O). I've used it here
>
> J. Phys. Chem. C 2010, 114, 21694
> J. Phys. Chem. C 2014, 118, 29928
>
> with apparently good results. I would suggest these values or
> something around:
>
> lda_plus_u=.true.,
> Hubbard_U(1)=3.2, <----Ti
> Hubbard_U(2)=2.0, <----O
>
> HTH
> Giuseppe
>
> Quoting Manu Hegde <mhegde at uwaterloo.ca>:
>
> > 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 <
> > giuseppe.mattioli at ism.cnr.it> 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 <degironc at sissa.it> 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
> >> >> <degironc at sissa.it <mailto:degironc at sissa.it>> 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)
> >> >>>
> >> >>>
> >> >>>
> >> >>>
> >> >>>
> >> >>>
> >> >>> _______________________________________________
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> >> >>
> >> >>
> >> >>
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> >> >>
> >> >>
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> >>
> >> 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: <giuseppe.mattioli at ism.cnr.it>
> >> http://www.ism.cnr.it/en/staff/giuseppe-mattioli/
> >> ResearcherID: F-6308-2012
> >>
> >>
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>
> --
> ********************************************************
> - 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: <giuseppe.mattioli at ism.cnr.it>
> http://www.ism.cnr.it/en/staff/giuseppe-mattioli/
> ResearcherID: F-6308-2012
>
>
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