<div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Dear Giuseppe,</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Thank you very much!</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Manu</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Aug 7, 2017 at 7:18 AM, Giuseppe Mattioli <span dir="ltr"><<a href="mailto:giuseppe.mattioli@ism.cnr.it" target="_blank">giuseppe.mattioli@ism.cnr.it</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><br>
Dear Manu<br>
<span class=""><br>
> Is EXX-ACE implemented in QE 6.1v by default or do I have to compile it<br>
> separately?.<br>
<br>
</span>Honestly, I would not give it for granted! Put the ACE flag in the<br>
make.inc file, it should not harm. :-)<br>
<span class=""><br>
> If I am not using HSE , do I have to use LDA level theory for TiO2 with<br>
> defects?.<br>
<br>
</span>Note that there are tons of papers on TiO2 defects. If you do not want<br>
to use EXX, then you can try with DFT+U(Ti,O). I've used it here<br>
<br>
J. Phys. Chem. C 2010, 114, 21694<br>
J. Phys. Chem. C 2014, 118, 29928<br>
<br>
with apparently good results. I would suggest these values or<br>
something around:<br>
<br>
lda_plus_u=.true.,<br>
Hubbard_U(1)=3.2, <----Ti<br>
Hubbard_U(2)=2.0, <----O<br>
<br>
HTH<br>
<span class="HOEnZb"><font color="#888888">Giuseppe<br>
</font></span><div class="HOEnZb"><div class="h5"><br>
Quoting Manu Hegde <<a href="mailto:mhegde@uwaterloo.ca">mhegde@uwaterloo.ca</a>>:<br>
<br>
> Hi Stefano and Giuseppe,<br>
><br>
> Thanks for your feedback.<br>
><br>
> I just wanted to try 48 atom supercell initially and see how it goes (to<br>
> save computation time as well). I will try 108 atom supercell definitely.<br>
><br>
> Is EXX-ACE implemented in QE 6.1v by default or do I have to compile it<br>
> separately?. I will try to run it (if our busy HPC facility permits!).<br>
><br>
> If I am not using HSE , do I have to use LDA level theory for TiO2 with<br>
> defects?.<br>
><br>
> Thanks<br>
> Manu<br>
> (University of Waterloo)<br>
><br>
> On Sun, Aug 6, 2017 at 6:08 PM, Giuseppe Mattioli <<br>
> <a href="mailto:giuseppe.mattioli@ism.cnr.it">giuseppe.mattioli@ism.cnr.it</a>> wrote:<br>
><br>
>><br>
>> On the top of Stefano's answer, I would add that in a 48 atom<br>
>> supercell the interaction between the relaxation sphere of an oxygen<br>
>> vacancy and its periodic images along the 100 or 010 directions is too<br>
>> strong and can lead to an improper description of the electronic<br>
>> properties of the defect that can not be considered as an "isolated<br>
>> defect" anymore. I suggest that you use at least a 3x3x1 108-atom<br>
>> supercell. With the new EXX-ACE implementation you may probably afford<br>
>> an HSE calculation, otherwise remember also that the small-polaron<br>
>> character of excess electrons in TiO2 such as those induced by the O<br>
>> vacancy is not at all well described at the GGA level of theory.<br>
>> HTH<br>
>> Giuseppe<br>
>><br>
>> stefano de gironcoli <<a href="mailto:degironc@sissa.it">degironc@sissa.it</a>> ha scritto:<br>
>><br>
>> > yes<br>
>> > start from the perfect relaxed geometry (as obtained from vc-relax)<br>
>> > remove an atom and relax the internal structure.<br>
>> > at the end also perform a vc-relaxation (from the fixed-cell relaxed<br>
>> > geometry)<br>
>> > stefano<br>
>> ><br>
>> > On 06/08/2017 17:33, Manu Hegde wrote:<br>
>> >> Hello Stephano,<br>
>> >> Thanks for your reply. Just to double check what you meant before<br>
>> >> starting the calculations, you mean take the equilibrium values<br>
>> >> from the vc-relax calculation (perfect cell, only co-ordinates)<br>
>> >> and do the 'relax' calculation with defect?.<br>
>> >> Manu<br>
>> >> (University of Waterloo).<br>
>> >><br>
>> >><br>
>> >> On Sun, Aug 6, 2017 at 11:15 AM, stefano de gironcoli<br>
>> >> <<a href="mailto:degironc@sissa.it">degironc@sissa.it</a> <mailto:<a href="mailto:degironc@sissa.it">degironc@sissa.it</a>>> wrote:<br>
>> >><br>
>> >> does the energy (enthalpy) decreases as the vc-relaxation<br>
>> >> progresses ?<br>
>> >> The local structure around the defect may be quite different. It<br>
>> >> may just take long.<br>
>> >><br>
>> >> I would start by performing a fixed cell relaxation with the cell<br>
>> >> parameters fixed at the undefected equilibrium values. And only<br>
>> >> after that I would start the vc-relax calculation from the so<br>
>> >> relaxed configuration to evaluate the vacancy formation volume.<br>
>> >> The local arrangement around the defect should be already more or<br>
>> >> less ok (if the supercell is large enough).<br>
>> >><br>
>> >> HTH<br>
>> >> stefano<br>
>> >><br>
>> >><br>
>> >><br>
>> >> On 06/08/2017 16:40, Manu Hegde wrote:<br>
>> >>> Hello,<br>
>> >>><br>
>> >>> I am trying to optimize anatase TiO2 supercell with 48 atoms. The<br>
>> >>> supercell converges in 15 BFGS cycles for a perfect cell. But<br>
>> >>> when I introduce defect (by removing one of the oxygen atom), the<br>
>> >>> vc-relax is not t all converging. I am using the same parameters<br>
>> >>> in both the cases. Can anyone give some feedback on this.?. Here<br>
>> >>> is my input,<br>
>> >>><br>
>> >>><br>
>> >>> &control<br>
>> >>> calculation = 'vc-relax' ,<br>
>> >>> restart_mode = 'from_scratch' ,<br>
>> >>> outdir = '/work/mhegde/tmp_tiodef/',<br>
>> >>> pseudo_dir = '/home/mhegde/tio_project/def_<wbr>tio/',<br>
>> >>> prefix = 'tioan',<br>
>> >>> verbosity = 'high',<br>
>> >>><br>
>> >>> /<br>
>> >>> &system<br>
>> >>> ibrav = 0,<br>
>> >>> nat = 47,<br>
>> >>> ntyp = 2,<br>
>> >>> ecutwfc =40,<br>
>> >>> ecutrho=400,<br>
>> >>> occupations='smearing',<br>
>> >>> degauss=0.003<br>
>> >>><br>
>> >>> /<br>
>> >>> &electrons<br>
>> >>> conv_thr = 1.D-6,<br>
>> >>> mixing_beta=0.1<br>
>> >>> /<br>
>> >>> &ions<br>
>> >>> ion_dynamics='bfgs'<br>
>> >>><br>
>> >>> /<br>
>> >>> &cell<br>
>> >>> cell_dynamics='bfgs'<br>
>> >>><br>
>> >>> /<br>
>> >>> ATOMIC_SPECIES<br>
>> >>> Ti 47.867000 Ti.pw91-nsp-van.UPF<br>
>> >>> O 15.99900 O.pw91-van_ak.UPF<br>
>> >>><br>
>> >>> ATOMIC_POSITIONS angstrom<br>
>> >>> Ti 0.00000000 2.84182500 1.20970000<br>
>> >>> Ti 1.89455000 2.84182500 3.62910000<br>
>> >>> O 0.00000000 0.94727500 1.99939216<br>
>> >>> O 0.00000000 2.84182500 4.41879216<br>
>> >>> O 1.89455000 0.94727500 2.83940784<br>
>> >>> Ti -1.89455000 0.94727500 -3.62910000<br>
>> >>> Ti 0.00000000 0.94727500 -1.20970000<br>
>> >>> O -1.89455000 -0.94727500 -2.83940784<br>
>> >>> O -1.89455000 0.94727500 -0.42000784<br>
>> >>> O 0.00000000 -0.94727500 -1.99939216<br>
>> >>> O 0.00000000 0.94727500 -4.41879216<br>
>> >>> Ti 0.00000000 -0.94727500 1.20970000<br>
>> >>> Ti 1.89455000 -0.94727500 3.62910000<br>
>> >>> O 0.00000000 -2.84182500 1.99939216<br>
>> >>> O 0.00000000 -0.94727500 4.41879216<br>
>> >>> O 1.89455000 -2.84182500 2.83940784<br>
>> >>> O 1.89455000 -0.94727500 0.42000784<br>
>> >>> Ti -1.89455000 -2.84182500 -3.62910000<br>
>> >>> Ti 0.00000000 -2.84182500 -1.20970000<br>
>> >>> O -1.89455000 2.84182500 -2.83940784<br>
>> >>> O -1.89455000 -2.84182500 -0.42000784<br>
>> >>> O 0.00000000 2.84182500 -1.99939216<br>
>> >>> O 0.00000000 -2.84182500 -4.41879216<br>
>> >>> Ti -3.78910000 2.84182500 1.20970000<br>
>> >>> Ti -1.89455000 2.84182500 3.62910000<br>
>> >>> O -3.78910000 0.94727500 1.99939216<br>
>> >>> O -3.78910000 2.84182500 4.41879216<br>
>> >>> O -1.89455000 0.94727500 2.83940784<br>
>> >>> O -1.89455000 2.84182500 0.42000784<br>
>> >>> Ti 1.89455000 0.94727500 -3.62910000<br>
>> >>> Ti -3.78910000 0.94727500 -1.20970000<br>
>> >>> O 1.89455000 -0.94727500 -2.83940784<br>
>> >>> O 1.89455000 0.94727500 -0.42000784<br>
>> >>> O -3.78910000 -0.94727500 -1.99939216<br>
>> >>> O -3.78910000 0.94727500 -4.41879216<br>
>> >>> Ti -3.78910000 -0.94727500 1.20970000<br>
>> >>> Ti -1.89455000 -0.94727500 3.62910000<br>
>> >>> O -3.78910000 -2.84182500 1.99939216<br>
>> >>> O -3.78910000 -0.94727500 4.41879216<br>
>> >>> O -1.89455000 -2.84182500 2.83940784<br>
>> >>> O -1.89455000 -0.94727500 0.42000784<br>
>> >>> Ti 1.89455000 -2.84182500 -3.62910000<br>
>> >>> Ti -3.78910000 -2.84182500 -1.20970000<br>
>> >>> O 1.89455000 2.84182500 -2.83940784<br>
>> >>> O 1.89455000 -2.84182500 -0.42000784<br>
>> >>> O -3.78910000 2.84182500 -1.99939216<br>
>> >>> O -3.78910000 -2.84182500 -4.41879216<br>
>> >>><br>
>> >>> K_POINTS {automatic}<br>
>> >>><br>
>> >>> 2 2 2 0 0 0<br>
>> >>><br>
>> >>> CELL_PARAMETERS angstrom<br>
>> >>><br>
>> >>> 7.57820000 0.00000000 0.00000000<br>
>> >>> 0.00000000 7.57820000 0.00000000<br>
>> >>> 0.00000000 0.00000000 9.67760000<br>
>> >>><br>
>> >>> Thanks,<br>
>> >>> Manu<br>
>> >>> (University of Waterloo)<br>
>> >>><br>
>> >>><br>
>> >>><br>
>> >>><br>
>> >>><br>
>> >>><br>
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>><br>
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>> CNR - ISTITUTO DI STRUTTURA DELLA MATERIA<br>
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******************************<wbr>**************************<br>
- Article premier - Les hommes naissent et demeurent<br>
libres et égaux en droits. Les distinctions sociales<br>
ne peuvent être fondées que sur l'utilité commune<br>
- Article 2 - Le but de toute association politique<br>
est la conservation des droits naturels et<br>
imprescriptibles de l'homme. Ces droits sont la liberté,<br>
la propriété, la sûreté et la résistance à l'oppression.<br>
******************************<wbr>**************************<br>
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Giuseppe Mattioli<br>
CNR - ISTITUTO DI STRUTTURA DELLA MATERIA<br>
v. Salaria Km 29,300 - C.P. 10<br>
I 00015 - Monterotondo Stazione (RM)<br>
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