Electronic SCF fails for oxide tio2

[satish2414]

Hello,
I am unable to optimize the following TiO2 nanotubes of different diameters. The electronic SCF does not converge within 60/100 NELM in any geometric step (see below).

$head -110 OSZICAR
N E dE d eps ncg rms rms(c)
DAV: 1 0.309554519125E+04 0.30955E+04 -0.82958E+04 1304 0.113E+03
DAV: 2 0.691793515914E+03 -0.24038E+04 -0.23451E+04 1656 0.295E+02
DAV: 3 -0.406283900955E+03 -0.10981E+04 -0.10795E+04 1848 0.193E+02
DAV: 4 -0.502274806916E+03 -0.95991E+02 -0.95707E+02 1848 0.729E+01
DAV: 5 -0.504466127320E+03 -0.21913E+01 -0.21895E+01 1896 0.110E+01 0.724E+01
DAV: 6 -0.421128794616E+03 0.83337E+02 -0.18802E+03 1864 0.786E+01 0.112E+02
DAV: 7 -0.334268361069E+03 0.86860E+02 -0.23519E+03 2000 0.873E+01 0.300E+01
DAV: 8 -0.350306242011E+03 -0.16038E+02 -0.43300E+02 1664 0.417E+01 0.348E+01
DAV: 9 -0.328179883401E+03 0.22126E+02 -0.37546E+01 1672 0.152E+01 0.248E+01
DAV: 10 -0.336078628418E+03 -0.78987E+01 -0.24678E+02 1880 0.235E+01 0.851E+01
DAV: 11 -0.322706019213E+03 0.13373E+02 -0.69252E+01 1896 0.140E+01 0.700E+01
DAV: 12 -0.313205313038E+03 0.95007E+01 -0.22838E+01 1896 0.103E+01 0.530E+01
DAV: 13 -0.312293061056E+03 0.91225E+00 -0.74973E+00 1856 0.451E+00 0.459E+01
DAV: 14 -0.313039708915E+03 -0.74665E+00 -0.25149E+00 1712 0.237E+00 0.471E+01
DAV: 15 -0.313786160114E+03 -0.74645E+00 -0.13124E+00 1640 0.184E+00 0.497E+01
DAV: 16 -0.314381252455E+03 -0.59509E+00 -0.14815E+00 1632 0.156E+00 0.538E+01
DAV: 17 -0.314826584298E+03 -0.44533E+00 -0.16328E+00 1624 0.183E+00 0.548E+01
DAV: 18 -0.314956478497E+03 -0.12989E+00 -0.42888E-01 1608 0.110E+00 0.551E+01
DAV: 19 -0.314983359336E+03 -0.26881E-01 -0.90492E-02 1680 0.443E-01 0.553E+01
DAV: 20 -0.314962700314E+03 0.20659E-01 -0.13695E-01 1712 0.465E-01 0.555E+01
DAV: 21 -0.314911135012E+03 0.51565E-01 -0.11979E-01 1624 0.359E-01 0.556E+01
DAV: 22 -0.314917882319E+03 -0.67473E-02 -0.81851E-02 1592 0.316E-01 0.557E+01
DAV: 23 -0.314987728334E+03 -0.69846E-01 -0.14349E-01 1616 0.393E-01 0.559E+01
DAV: 24 -0.315052010967E+03 -0.64283E-01 -0.18402E-01 1592 0.403E-01 0.561E+01
DAV: 25 -0.315084911233E+03 -0.32900E-01 -0.20611E-01 1640 0.507E-01 0.563E+01
DAV: 26 -0.315139391915E+03 -0.54481E-01 -0.16252E-01 1632 0.486E-01 0.564E+01
DAV: 27 -0.315215609241E+03 -0.76217E-01 -0.14517E-01 1600 0.439E-01 0.565E+01
DAV: 28 -0.315383562502E+03 -0.16795E+00 -0.16404E-01 1672 0.577E-01 0.566E+01
DAV: 29 -0.315322415501E+03 0.61147E-01 -0.15473E-01 1632 0.481E-01 0.566E+01
DAV: 30 -0.315329332107E+03 -0.69166E-02 -0.10655E-01 1600 0.380E-01 0.566E+01
DAV: 31 -0.315286249569E+03 0.43083E-01 -0.11057E-01 1736 0.539E-01 0.564E+01
DAV: 32 -0.314823398902E+03 0.46285E+00 -0.23095E-01 1880 0.124E+00 0.559E+01
DAV: 33 -0.314714571469E+03 0.10883E+00 -0.12402E-01 1696 0.612E-01 0.557E+01
DAV: 34 -0.314718989705E+03 -0.44182E-02 -0.44906E-02 1640 0.272E-01 0.557E+01
DAV: 35 -0.314837834620E+03 -0.11884E+00 -0.31030E-02 1656 0.290E-01 0.558E+01
DAV: 36 -0.315154332725E+03 -0.31650E+00 -0.33800E-02 1752 0.377E-01 0.560E+01
DAV: 37 -0.314905379499E+03 0.24895E+00 -0.25441E-02 1688 0.370E-01 0.559E+01
DAV: 38 -0.314421057420E+03 0.48432E+00 -0.77542E-01 1888 0.259E+00 0.557E+01
DAV: 39 -0.313146088810E+03 0.12750E+01 -0.67584E-01 1880 0.196E+00 0.550E+01
DAV: 40 -0.312577857527E+03 0.56823E+00 -0.19034E-01 1696 0.837E-01 0.542E+01
DAV: 41 -0.312545067273E+03 0.32790E-01 -0.13489E-01 1640 0.489E-01 0.539E+01
DAV: 42 -0.311990100611E+03 0.55497E+00 -0.50645E-01 1856 0.140E+00 0.526E+01
DAV: 43 -0.310017418878E+03 0.19727E+01 -0.15088E+00 1952 0.273E+00 0.492E+01
DAV: 44 -0.305977710117E+03 0.40397E+01 -0.46324E+00 1944 0.528E+00 0.381E+01
DAV: 45 -0.307474635082E+03 -0.14969E+01 -0.43803E+00 1704 0.359E+00 0.322E+01
DAV: 46 -0.307873916205E+03 -0.39928E+00 -0.27601E+00 1656 0.283E+00 0.267E+01
DAV: 47 -0.308998673312E+03 -0.11248E+01 -0.31984E+00 1664 0.309E+00 0.253E+01
DAV: 48 -0.309569408706E+03 -0.57074E+00 -0.70022E-01 1600 0.168E+00 0.251E+01
DAV: 49 -0.309674796759E+03 -0.10539E+00 -0.18673E-01 1624 0.811E-01 0.251E+01
DAV: 50 -0.309798554131E+03 -0.12376E+00 -0.10261E-01 1776 0.672E-01 0.252E+01
DAV: 51 -0.319305672185E+03 -0.95071E+01 -0.39274E+01 1792 0.187E+01 0.469E+01
DAV: 52 -0.320989383202E+03 -0.16837E+01 -0.89787E+00 1712 0.658E+00 0.503E+01
DAV: 53 -0.321356559733E+03 -0.36718E+00 -0.88228E-01 1744 0.218E+00 0.518E+01
DAV: 54 -0.326727258999E+03 -0.53707E+01 -0.12128E+00 1664 0.349E+00 0.543E+01
DAV: 55 -0.326808948553E+03 -0.81690E-01 -0.24776E-01 1528 0.135E+00 0.544E+01
DAV: 56 -0.306718658124E+03 0.20090E+02 -0.46154E+01 1816 0.231E+01 0.349E+01
DAV: 57 -0.308123652957E+03 -0.14050E+01 -0.20051E+01 1784 0.108E+01 0.284E+01
DAV: 58 -0.308247139690E+03 -0.12349E+00 -0.63361E+00 1920 0.604E+00 0.260E+01
DAV: 59 -0.308542654565E+03 -0.29551E+00 -0.20516E+00 1864 0.317E+00 0.247E+01
DAV: 60 -0.309119899165E+03 -0.57724E+00 -0.18393E+00 1736 0.227E+00 0.251E+01
DAV: 61 -0.307824902156E+03 0.12950E+01 -0.98885E+00 1824 0.826E+00 0.161E+01
DAV: 62 -0.307683846262E+03 0.14106E+00 -0.36892E+00 1872 0.461E+00 0.129E+01
DAV: 63 -0.307425709719E+03 0.25814E+00 -0.85408E-01 1768 0.221E+00 0.116E+01
DAV: 64 -0.307343493517E+03 0.82216E-01 -0.19516E-01 1792 0.982E-01 0.112E+01
DAV: 65 -0.307111798618E+03 0.23169E+00 -0.61390E-01 1952 0.149E+00 0.102E+01
DAV: 66 -0.307019277225E+03 0.92521E-01 -0.12573E+00 1864 0.251E+00 0.115E+01
DAV: 67 -0.307027078803E+03 -0.78016E-02 -0.71167E-01 1864 0.179E+00 0.938E+00
DAV: 68 -0.307324205839E+03 -0.29713E+00 -0.32065E-01 1680 0.118E+00 0.975E+00
DAV: 69 -0.307405465197E+03 -0.81259E-01 -0.15579E-01 1664 0.616E-01 0.990E+00
DAV: 70 -0.307366077325E+03 0.39388E-01 -0.60183E-02 1792 0.543E-01 0.961E+00
DAV: 71 -0.307308751715E+03 0.57326E-01 -0.11126E+00 1928 0.208E+00 0.101E+01
DAV: 72 -0.307238241452E+03 0.70510E-01 -0.21528E-01 1792 0.973E-01 0.946E+00
DAV: 73 -0.307146591071E+03 0.91650E-01 -0.18047E-01 1880 0.818E-01 0.914E+00
DAV: 74 -0.307124999763E+03 0.21591E-01 -0.15393E-01 1784 0.713E-01 0.912E+00
DAV: 75 -0.307186115924E+03 -0.61116E-01 -0.16343E-01 1816 0.741E-01 0.910E+00
DAV: 76 -0.307241958381E+03 -0.55842E-01 -0.58687E-01 1936 0.205E+00 0.102E+01
DAV: 77 -0.307206974573E+03 0.34984E-01 -0.15364E-01 1776 0.888E-01 0.970E+00
DAV: 78 -0.307176444245E+03 0.30530E-01 -0.13589E-01 1808 0.809E-01 0.992E+00
DAV: 79 -0.307107509937E+03 0.68934E-01 -0.93929E-02 1840 0.752E-01 0.991E+00
DAV: 80 -0.307140101748E+03 -0.32592E-01 -0.44921E-02 1744 0.420E-01 0.101E+01
DAV: 81 -0.307439111952E+03 -0.29901E+00 -0.94058E-01 1936 0.226E+00 0.143E+01
DAV: 82 -0.307281348400E+03 0.15776E+00 -0.98326E-01 1864 0.230E+00 0.152E+01
DAV: 83 -0.307306457246E+03 -0.25109E-01 -0.73575E-01 1736 0.151E+00 0.167E+01
DAV: 84 -0.307594254594E+03 -0.28780E+00 -0.14409E+00 1704 0.115E+00 0.189E+01
DAV: 85 -0.307852960263E+03 -0.25871E+00 -0.45050E-01 1608 0.101E+00 0.192E+01
DAV: 86 -0.307564364299E+03 0.28860E+00 -0.75349E+00 1952 0.710E+00 0.294E+01
DAV: 87 -0.306598057346E+03 0.96631E+00 -0.12917E+01 1992 0.648E+00 0.184E+01
DAV: 88 -0.306388581928E+03 0.20948E+00 -0.26351E+00 1904 0.331E+00 0.146E+01
DAV: 89 -0.306167631698E+03 0.22095E+00 -0.76214E-01 1856 0.163E+00 0.127E+01
DAV: 90 -0.306076295843E+03 0.91336E-01 -0.36156E-01 1792 0.133E+00 0.115E+01
DAV: 91 -0.306115506587E+03 -0.39211E-01 -0.11004E+00 2000 0.176E+00 0.117E+01
DAV: 92 -0.306228500501E+03 -0.11299E+00 -0.63180E-01 1776 0.157E+00 0.101E+01
DAV: 93 -0.306464669277E+03 -0.23617E+00 -0.29377E-01 1696 0.117E+00 0.989E+00
DAV: 94 -0.306588602077E+03 -0.12393E+00 -0.18803E-01 1664 0.741E-01 0.996E+00
DAV: 95 -0.306607423551E+03 -0.18821E-01 -0.79234E-02 1672 0.484E-01 0.991E+00
DAV: 96 -0.306323687232E+03 0.28374E+00 -0.63333E-01 2008 0.269E+00 0.996E+00
DAV: 97 -0.306174387497E+03 0.14930E+00 -0.25688E-01 1840 0.124E+00 0.976E+00
DAV: 98 -0.306141898607E+03 0.32489E-01 -0.12125E-01 1952 0.102E+00 0.954E+00
DAV: 99 -0.306141885939E+03 0.12667E-04 -0.68554E-01 1976 0.236E+00 0.102E+01
DAV: 100 -0.306355179047E+03 -0.21329E+00 -0.34218E-01 1840 0.125E+00
1 F= -.30635518E+03 E0= -.30623187E+03 d E =-.306355E+03
likewise for next subsequent steps
------------------------
INCAR:
SYSTEM = TiO2

ISTART = 0
ISMEAR = 0
SIGMA = 0.1
IBRION = 2
NSW = 500
ENCUT = 450 eV
PREC = normal
GGA = 91
ISIF = 2
EDIFF = 1E-5
EDIFFG = -0.01
LWAVE = T
LCHARG = T
NPAR=4

#------------- U parameters ----------
LDAU = .True.
LDAUTYPE = 2
LDAUL = 2 -1
LDAUJ = 1 0
LDAUU = 5 0
---------------------------------

Some of the parameters I tested that did not help in optimizing the geometry:
1) Calculations without U parameter
# following are calculations without U
2) IBRION =1
3) ALGO = Fast
4) Increased vacuum size in POSCAR
5) ISYM =0
6) LREAL = Auto
7) increase NELM form the default 60 to 100.
------------------------------
POSCAR:

Ti O
1.0000000000000000
25.0000000000000000 0.0000000000000000 0.0000000000000000
0.0000000000000000 25.0000000000000000 0.0000000000000000
0.0000000000000000 0.0000000000000000 3.8227608202801915
16 32
Cartesian
14.3910089583333320 19.5518820833333322 0.9556904101400961
13.7965989583333322 17.3344420833333359 2.8670704101400961
18.8264989583333318 16.1465520833333329 0.9556904101400961
16.8378589583333316 14.9995320833333334 2.8670704101400961
19.5531789583333335 10.6020320833333344 0.9556904101400961
17.3361189583333335 11.1978420833333345 2.8670704101400961
16.1450489583333336 6.1687020833333337 0.9556904101400961
14.9992789583333330 8.1580620833333342 2.8670704101400961
10.6000689583333330 5.4455220833333335 0.9556904101400961
11.1972889583333330 7.6622020833333337 2.8670704101400961
6.1688889583333326 8.8564520833333340 0.9556904101400961
8.1589789583333321 10.0009620833333344 2.8670704101400961
5.4492189583333328 14.4018920833333333 0.9556904101400961
7.6655289583333328 13.8032720833333347 2.8670704101400961
8.8629489583333321 18.8309120833333346 0.9556904101400961
10.0061989583333322 16.8401020833333348 2.8670704101400961
14.2911589583333321 19.1793820833333335 2.8670704101400961
15.3146989583333326 16.1636920833333342 2.8670704101400961
17.1824189583333329 18.5964220833333336 0.9556904101400961
13.8964489583333322 17.7069420833333346 0.9556904101400961
18.4924389583333308 15.9538720833333336 2.8670704101400961
17.0828689583333322 13.0981520833333338 2.8670704101400961
20.1238789583333322 13.4967120833333336 0.9556904101400961
17.1719189583333325 15.1922120833333345 0.9556904101400961
19.1807489583333322 10.7021220833333341 2.8670704101400961
16.1644089583333326 9.6804820833333345 2.8670704101400961
18.5959589583333340 7.8112220833333339 0.9556904101400961
17.7085489583333313 11.0977520833333330 0.9556904101400961
15.9525789583333335 6.5028820833333336 2.8670704101400961
13.0977489583333320 7.9142520833333343 2.8670704101400961
13.4943889583333316 4.8729920833333340 0.9556904101400961
15.1917589583333328 7.8238820833333342 0.9556904101400961
10.7003989583333325 5.8178920833333336 2.8670704101400961
9.6806689583333316 8.8348720833333338 2.8670704101400961
7.8098689583333325 6.4045020833333339 0.9556904101400961
11.0969589583333317 7.2898320833333337 0.9556904101400961
6.5031989583333321 9.0487120833333350 2.8670704101400961
7.9163689583333321 11.9026520833333347 2.8670704101400961
4.8748589583333324 11.5079320833333334 0.9556904101400961
7.8246689583333326 9.8087020833333334 0.9556904101400961
5.8215289583333325 14.3013320833333335 2.8670704101400961
8.8391589583333321 15.3191520833333339 2.8670704101400961
6.4099689583333328 17.1914820833333337 0.9556904101400961
7.2932189583333322 13.9038320833333344 0.9556904101400961
9.0549989583333321 18.4964820833333334 2.8670704101400961
11.9080489583333318 17.0815020833333335 2.8670704101400961
11.5152489583333324 20.1232620833333335 0.9556904101400961
9.8141489583333321 17.1745220833333327 0.9556904101400961
--------

Thank you for any help.

[szvasp]

I am not sure if really the charge density of your system get any dramatic update toward convergence or not, as you have hired the blocked Davidson algorithm for electronic convergence in a nanotubes. I would recommend to use for example RMM-DIIS algorithm with a proper NELMDL (e.g: NELMDL = -15 ) to give some numbers of non-selfconsistent steps at the beginning of starting-configuration of electronic convergence, it usually helps in systems like surfaces ... .

Cheers,

Salman Zarrini

[alex]

Hi satish2414,

your structure is far away from a classical titania, e.g. the terminating O atoms are about 3 \AA apart from the next neighbor.

Maybe you are more successful if you allow (or put them deliberately) spin on these O atoms.

Good luck!

alex

[satish2414]

Thank you for the suggestions.

@Salman, I tried RMM-DIIS and DAV with NELMDL=-15. Both worked but only for PW91 XC but both failed when I include the U parameters.

@Alex, Did you mean something like including MAGMOM = 16*0 32*0.3 in the INCAR? I suppose this tag would mean no magnetic moment on the 16 Ti atoms but 0.3 mu_B for each of the 32 O atoms (am I right?). Here I mention a small magnetic moment of 0.3 mu_B so that during the electronic minimization a non magnetic ground state may be obtained (as I am interested in a non-magnetic solution). Not sure if this is what you meant, but doing so I still could not get the electronic minimization converged even with NELM=100.

Thank you for your thoughts again.

[satish2414]

So, I started from scratch with a completely new geometry, which worked!