[Pw_forum] Help with atomic relaxation (Issue with convergence)
Vikas Varshney
vv0210 at gmail.com
Tue Jan 31 15:05:18 CET 2012
Dear Guido, Paolo, Giuseppe
I just wanted to tell you guys (and put this in the forum) that gaussian
smearing with low convergence (1e-5) worked for Ni layer relaxation on
Al2O3 slab as first step (with K meshing of 4 4 1). Later, I increased
the convergence to 1e-8 and the runs finished successfully as well. Thanks
for all your help and guidance.
Best Regards,
Vikas
Getting ready for next set of simulations.
On Tue, Jan 24, 2012 at 11:14 AM, Guido Fratesi <fratesi at mater.unimib.it>wrote:
> I have not tired gaussian smearing. I will try that as well. I will also
>> reduce the k-mesh style to get to final coordinates quicker.
>> How do I specify larger broadening. Sorry but I am new to QE so please
>> help here.
>>
>
> sorry, it's the parameter called "degauss"
>
>
> Yes you are very true to say that Ni Atoms are a bit closer than their
>> respective positions in crystal. As I wanted to lay down a Ni layer of
>> Al2O3, I started with 1 1 1 plane of Ni (hexagonal symmetry) with to put
>> on top of Al2O3 (hexagonal symmetry). However as you see below, the unit
>> cell of Al2O3 is a little smaller than that of Ni, so, I compressed the
>> Ni atoms a little bit so as to fit them in Al2O3 geometry.
>> Al2O3 a cell dimension = 4.789471
>> Ni a cell dimension (along 1 1 1) plane = 4.951255
>>
>
> well, not that much indeed. Still some buckling could be expected, as you
> say below.
>
>
> I could now very well see that is this could be a source of the problem.
>> In that case, what do you suggest? What about moving 2 of the 4 atoms in
>> z direction so that distance between the atoms becomes similar to ~ what
>> it is in bulk crystal. I had nspin=2 (default) in my calculations.
>>
>
> in the input posted to the forum there was no spin polarization. The
> default is nspin=1.
>
> Regards,
> Guido
>
> Should I change it to nspin = 1?
>> Thank you very much for the insights.
>> Best Regards,
>> Vikas
>> On Tue, Jan 24, 2012 at 10:35 AM, Guido Fratesi <fratesi at mater.unimib.it
>> <mailto:fratesi at mater.unimib.**it <fratesi at mater.unimib.it>>> wrote:
>>
>> Have you tried with gaussian smearing, by chance? In a test I was
>> making sometimes ago with TiO2 slabs, that was more easy to converge
>> than the other choices. A larger broadening could also help,
>> especially to get an initial configuration/charge to be refined
>> later, and you might want to reduce the kpoint mesh to speed up your
>> tests. Ni atoms look a bit (not too much) close which could be also
>> source of problems: is the Ni overlayer compressed with respect to a
>> free-standing Ni layer in 2D? Finally, I guess you will be
>> interested in spin-polarized calculations at the end.
>> I'd be curious about what solves the problem, eventually.
>> Guido
>>
>> Il 01/24/2012 03:48 PM, Vikas Varshney ha scritto:
>>
>> Dear Guido,
>> Sorry for the confusion, actually when I was copy pasting the
>> data on
>> the email from my input file, 3 lines got deleted by error.
>> Number of
>> atoms are actually 34. 30 Al203 atoms for a unit cell and 4 Ni
>> atoms.
>> THe full positions are below.The bold lines were missing before.
>> Thanks
>> for looking into this.
>> ATOMIC_POSITIONS angstrom
>> O 1.473346033 0.017326072 3.218609176
>> O 3.863581042 <tel:3.863581042> 1.378379317 7.574956508
>> <tel:7.574956508>
>> O 1.513480866 2.829876285 11.933514340
>> O -0.751677351 1.267293591 3.218609163
>> O 1.663968734 2.656771683 7.574956486
>> O -0.812749430 4.043578468 11.933514157
>> O 1.673065193 2.863185205 3.218609361
>> O 1.656654190 0.112656124 7.574956554
>> O -0.700731568 1.422153909 11.933514350
>> O 3.298048338 0.005706615 9.773211485
>> O 0.927961928 1.382600916 1.089494747 0 0 0
>> O -1.464820834 2.766734881 5.396064047
>> O -1.653964847 2.853342545 9.773211296
>> O 3.128121670 <tel:3.128121670> 0.112338146 1.089494747 0
>> 0 0
>> O 0.731082457 1.495864856 5.396064158
>> *O 0.750650394 1.288758309 9.773211044
>>
>> O 3.128121627 <tel:3.128121627> 2.652863759 1.089494747 0
>>
>> 0 0
>> O 0.733736896 4.033006936 5.396064408
>> *Al -0.000000812 0.000001493 4.556157709
>>
>> Al 2.394734647 <tel:2.394734647> 1.382602298 8.876166342
>> Al 0.000000000 2.765201880 0.243870515 0 0 0
>> Al 0.000000000 0.000000000 1.935118618 0 0 0
>> Al 2.394734540 <tel:2.394734540> 1.382602230 6.225550857
>>
>> Al -0.000000007 2.765202952 10.790402310
>> Al -0.000000362 0.000002278 8.430662634
>> Al 2.394735475 <tel:2.394735475> 1.382602563 12.021576409
>>
>> Al -0.000000581 2.765202130 4.047340256
>> Al 0.000000075 0.000002190 11.054412333
>> Al 2.394734840 <tel:2.394734840> 1.382601177 2.258435418
>> <tel:2.258435418>
>>
>> Al -0.000000323 2.765202460 6.730673987
>> Ni -0.016734 -0.025515 15.297379
>> Ni 1.180634 -2.099417 15.297379
>> Ni -1.214101 -2.099417 15.297379
>> Ni -2.411469 -0.025515 15.297379
>> Best Regards,
>> Vikas
>>
>> On Tue, Jan 24, 2012 at 3:46 AM, Guido Fratesi
>> <fratesi at mater.unimib.it <mailto:fratesi at mater.unimib.**it<fratesi at mater.unimib.it>
>> >
>> <mailto:fratesi at mater.unimib._**_it
>>
>> <mailto:fratesi at mater.unimib.**it <fratesi at mater.unimib.it>>>>
>> wrote:
>>
>> Have you checked the input is read correctly? Apparently,
>> the number of
>> atoms listed (31) does not correspond to "nat" (ii)
>> Guido
>>
>> Il 01/23/2012 06:51 PM, Vikas Varshney ha scritto:
>> > &CONTROL
>> > calculation = 'relax' ,
>> > restart_mode = 'from_scratch' ,
>> > wf_collect = .true. ,
>> > outdir = './' ,
>> > pseudo_dir =
>> '/lustre/app2/espresso/pseudo/**__' ,
>>
>> > disk_io = 'default' ,
>> > verbosity = 'high' ,
>> > /
>> > &SYSTEM
>> > ibrav = 0,
>> > celldm(1)= 9.050787,
>> > nat = 34,
>> > ntyp = 3,
>> > ecutwfc = 55 ,
>> > ecutrho = 550 ,
>> > occupations = 'smearing' ,
>> > degauss = 0.01 ,
>> > smearing = 'methfessel-paxton' ,
>> > nosym = .true. ,
>> > nosym_evc = .true. ,
>> > /
>> > &ELECTRONS
>> > conv_thr = 1.0D-4 ,
>> > diagonalization = 'david' ,
>> > mixing_mode = 'local-TF' ,
>> > mixing_beta = 0.1 ,
>> > electron_maxstep = 500 ,
>> > /
>> > &IONS
>> > ion_dynamics = 'bfgs' ,
>> > ion_positions = 'from_input' ,
>> > /
>> > CELL_PARAMETERS hexagonal
>> > 1.000000000 0.000000000 0.000000000
>> > 0.500000000 0.866025000 0.000000000
>> > 0.000000000 0.000000000 10.824313000
>> > ATOMIC_SPECIES
>> > O 15.99940 O.pbe-van_ak.UPF
>> > Al 26.98154 Al.pbe-n-van.UPF
>> > Ni 58.69340 Ni.pbe-nd-rrkjus.UPF
>> > ATOMIC_POSITIONS angstrom
>> > O 1.473346033 0.017326072 3.218609176
>> > O 3.863581042 <tel:3.863581042> <tel:3.863581042
>>
>> <tel:3.863581042>> 1.378379317 7.574956508 <tel:7.574956508>
>> <tel:7.574956508 <tel:7.574956508>>
>>
>>
>> > O 1.513480866 2.829876285 11.933514340
>> > O -0.751677351 1.267293591 3.218609163
>> > O 1.663968734 2.656771683 7.574956486
>> > O -0.812749430 4.043578468 11.933514157
>> > O 1.673065193 2.863185205 3.218609361
>> > O 1.656654190 0.112656124 7.574956554
>> > O -0.700731568 1.422153909 11.933514350
>> > O 3.298048338 0.005706615 9.773211485
>> > O 0.927961928 1.382600916 1.089494747 0 0 0
>> > O -1.464820834 2.766734881 5.396064047
>> > O -1.653964847 2.853342545 9.773211296
>> > O 3.128121670 <tel:3.128121670> <tel:3.128121670
>>
>> <tel:3.128121670>> 0.112338146 1.089494747 0
>>
>> 0 0
>> > O 0.731082457 1.495864856 5.396064158
>> > Al -0.000000812 0.000001493 4.556157709
>> > Al 2.394734647 <tel:2.394734647> <tel:2.394734647
>>
>> <tel:2.394734647>> 1.382602298 8.876166342
>>
>> > Al 0.000000000 2.765201880 0.243870515 0 0 0
>> > Al 0.000000000 0.000000000 1.935118618 0 0 0
>> > Al 2.394734540 <tel:2.394734540> 1.382602230 6.225550857
>>
>> > Al -0.000000007 2.765202952 10.790402310
>> > Al -0.000000362 0.000002278 8.430662634
>> > Al 2.394735475 <tel:2.394735475> 1.382602563 12.021576409
>>
>> > Al -0.000000581 2.765202130 4.047340256
>> > Al 0.000000075 0.000002190 11.054412333
>> > Al 2.394734840 <tel:2.394734840> 1.382601177 2.258435418
>> <tel:2.258435418>
>>
>> > Al -0.000000323 2.765202460 6.730673987
>> > Ni -0.016734 -0.025515 15.297379
>> > Ni 1.180634 -2.099417 15.297379
>> > Ni -1.214101 -2.099417 15.297379
>> > Ni -2.411469 -0.025515 15.297379
>> > K_POINTS automatic
>> > 4 4 1 0 0 0
>>
>> --
>> Guido Fratesi
>>
>> Dipartimento di Scienza dei Materiali
>> Universita` degli Studi di Milano-Bicocca
>> via Cozzi 53, 20125 Milano, Italy
>> ______________________________**___________________
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>>
>>
>> --
>> Guido Fratesi
>>
>> Dipartimento di Scienza dei Materiali
>> Universita` degli Studi di Milano-Bicocca
>> via Cozzi 53, 20125 Milano, Italy
>>
>>
>>
> --
> Guido Fratesi
>
> Dipartimento di Scienza dei Materiali
> Universita` degli Studi di Milano-Bicocca
> via Cozzi 53, 20125 Milano, Italy
>
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