[Pw_forum] SCF do not converge

Regina Lelis de Sousa rlsousa at mail.uft.edu.br
Wed Jul 20 15:34:26 CEST 2016


Dear all,
I am studying Pt(111) and Pt(100) surfaces (using a slab model) with PWSCF.
I ran a structural relaxations for slabs containing 4 - 9 atomic planes
(layers) and everything was fine. In all calculations a vacuum region of
the order of 15 Angstroms was  used. However, in the calculations with 10
atomic planes or more the SCF procedure does not converge and i do not
understand the reason. I did some changes on SCF procedure (for example: I
tested cg method among other things). Does anyone notice some mistake with
the input file or with my atomic coordinates?  Any help would be
appreciated.


 The  inputs and outputs are:

1 - First Try:
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
&control
    calculation = 'relax'
    restart_mode='from_scratch',
    prefix='Pt_100_12_layers_15_vacuo',
    tprnfor = .true.,
    tstress =.true.,
    verbosity ='high',
    pseudo_dir = '/home/rlsousa/Pseudopot',
 /
 &system
    ibrav=  6,
A = 2.831157456,
C=37.2,
    nat=  12,
    ntyp= 1,
    ecutwfc =35.0,
    ecutrho = 350.0,
    occupations='smearing',
    smearing='marzari-vanderbilt',
    degauss=0.01, !I tested this.
 /
 &electrons
    mixing_beta = 0.7,
    conv_thr =  1.0d-8
electron_maxstep = 600,
 /
&ions
/
ATOMIC_SPECIES
Pt  195.084 Pt.pbe-nd-rrkjus.UPF
ATOMIC_POSITIONS {angstrom}
Pt    0.000000    0.000000    0.000000
Pt    1.414214    1.414214    2.000000
Pt    0.000000    0.000000    4.000000
Pt    1.414214    1.414214    6.000000
Pt    0.000000    0.000000    8.000000
Pt    1.414214    1.414214    10.000000
Pt    0.000000    0.000000    12.000000
Pt    1.414214    1.414214    14.000000
Pt    0.000000    0.000000    16.000000
Pt    1.414214    1.414214    18.000000
Pt    0.000000    0.000000    20.000000
Pt    1.414214    1.414214    22.000000
K_POINTS AUTOMATIC
16 16 1 1 1 1
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
OUTPUT:

     Program PWSCF v.5.0.1 starts on  3Mar2016 at  1:58: 2
...

...

     Self-consistent Calculation

     iteration #  1     ecut=    35.00 Ry     beta=0.70
     Davidson diagonalization with overlap
     ethr =  1.00E-02,  avg # of iterations =  4.0

     total cpu time spent up to now is      212.7 secs

     total energy              =   -1037.38592080 Ry
     Harris-Foulkes estimate   =   -1039.73360971 Ry
     estimated scf accuracy    <       2.83017780 Ry

     iteration #  2     ecut=    35.00 Ry     beta=0.70
     Davidson diagonalization with overlap
     ethr =  2.36E-03,  avg # of iterations =  8.9

     total cpu time spent up to now is      627.5 secs

     total energy              =   -1004.47885510 Ry
     Harris-Foulkes estimate   =   -1113.67210149 Ry
     estimated scf accuracy    <    4035.50057863

...


     iteration #600     ecut=    35.00 Ry     beta=0.70
     Davidson diagonalization with overlap
     ethr =  2.92E-05,  avg # of iterations = 11.5

     total cpu time spent up to now is   250301.6 secs

     total energy              =   -1025.14170975 Ry
     Harris-Foulkes estimate   =   -1050.93732899 Ry
     estimated scf accuracy    <     312.87625423 Ry

     End of self-consistent calculation

     convergence NOT achieved after 600 iterations: stopping


===================================================================================
=   BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES
=   EXIT CODE: 1
=   CLEANING UP REMAINING PROCESSES
=   YOU CAN IGNORE THE BELOW CLEANUP MESSAGES
===================================================================================

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2 - Second Try:
I did:
 &electrons
diagonalization='cg'
    mixing_beta = 0.5,
    conv_thr =  1.0d-8
electron_maxstep = 300,

and this work fine only for Pt(100) with 10 atomic plane.

$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
3 - Third Try:
For Pt(111) with 10 atomic planes:
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
 &control
    calculation = 'relax'
    restart_mode='from_scratch',
    prefix='Pt_111_10_layers',
    tprnfor = .true.,
    tstress =.true.,
    verbosity ='high',
    pseudo_dir = '/home/rlsousa/pseudo/'
 /
 &system
    ibrav=  4,
A = 2.831157456,
C=36.0,
    nat=  10,
    ntyp= 1,
    ecutwfc =35.0,
    ecutrho = 350.0,
    occupations='smearing',
    smearing='marzari-vanderbilt',
    degauss=0.01,
 /
 &electrons
    mixing_beta = 0.7,
    conv_thr =  1.0d-8
electron_maxstep = 600,
 /
&ions
/
ATOMIC_SPECIES
Pt  195.084 Pt.pbe-nd-rrkjus.UPF
ATOMIC_POSITIONS {angstrom}
Pt -0.000000000 -0.000000000 -20.784609691
Pt 0.000000000 -0.000000000 -13.856406461
Pt 0.000000000 -0.000000000 -6.928203230
Pt 0.000000000 0.000000000 0.000000000
Pt 1.414213562 0.816496581 -16.165807537
Pt 1.414213562 0.816496581 -9.237604307
Pt 1.414213562 0.816496581 -2.309401077
Pt -0.000000000 1.632993162 -18.475208614
Pt -0.000000000 1.632993162 -11.547005384
Pt -0.000000000 1.632993162 -4.618802154
K_POINTS AUTOMATIC
16 16 1 1 1 1
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
And the output is:
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
     Self-consistent Calculation

     iteration #  1     ecut=    35.00 Ry     beta=0.70
     Davidson diagonalization with overlap
     ethr =  1.00E-02,  avg # of iterations =  3.7

     total cpu time spent up to now is      619.8 secs

     total energy              =    -864.90667968 Ry
     Harris-Foulkes estimate   =    -866.46381391 Ry
     estimated scf accuracy    <       1.92161923 Ry

     iteration #  2     ecut=    35.00 Ry     beta=0.70
     Davidson diagonalization with overlap
     ethr =  1.92E-03,  avg # of iterations =  8.8

     total cpu time spent up to now is     1789.4 secs

     total energy              =    -834.69092069 Ry
     Harris-Foulkes estimate   =    -912.73406647 Ry
     estimated scf accuracy    <    3297.67106012 Ry
    iteration #154     ecut=    35.00 Ry     beta=0.70
     Davidson diagonalization with overlap
     ethr =  8.37E-05,  avg # of iterations =  7.2

     negative rho (up, down):  0.577E-07 0.000E+00

     total cpu time spent up to now is   143089.7 secs

     total energy              =    -862.54326840 Ry
     Harris-Foulkes estimate   =    -876.81955048 Ry
     estimated scf accuracy    <     354.34333068 Ry

     iteration #155     ecut=    35.00 Ry     beta=0.70
     Davidson diagonalization with overlap
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

4 - fourth Try:
The atomic positions for input file was optimized with a PCFF force field:
a - For Pt(100) with 16 atomic planes, the atomic positions for input were:
Pt 0.000001863 -0.000006550 1.917081940
Pt -0.000000583 -0.000002969 5.858730954
Pt -0.000001806 0.000000728 9.775507899
Pt -0.000003453 0.000006845 13.688807549
Pt -0.000001863 0.000006007 17.601709335
Pt -0.000000324 0.000000339 21.516053222
Pt 0.000003440 -0.000003229 25.439026038
Pt 0.000005016 -0.000002994 29.455726011
Pt 1.382821195 1.382814326 -0.121704445
Pt 1.382818575 1.382816058 3.895001445
Pt 1.382817093 1.382818978 7.817973036
Pt 1.382816565 1.382824166 11.732314256
Pt 1.382814960 1.382827050 15.645213637
Pt 1.382818406 1.382822391 19.558517247
Pt 1.382820459 1.382816862 23.475296312
Pt 1.382823964 1.382815499 27.416943612

But I get the same result.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
5 - fifth try - I did not have any throuble for these cases.
a - For Pt(100) with 9 atomic planes:
$$$$$$$$$$$$$$$$$$$$$$$$$$$
.....
 &system
    ibrav=  6,
A = 2.831157456,
C=33.2,
    nat=  9,
    ntyp= 1,
    ecutwfc =35.0,
    ecutrho = 350.0,
    occupations='smearing',
    smearing='marzari-vanderbilt',
    degauss=0.01,
 /
 &electrons
diagonalization='cg'
    mixing_beta = 0.5,
    conv_thr =  1.0d-8
electron_maxstep = 300,
 /
&ions
/
ATOMIC_SPECIES
Pt  195.084 Pt.pbe-nd-rrkjus.UPF
ATOMIC_POSITIONS {angstrom}
Pt 0.000000000 -0.000000000 2.001930636
Pt 0.000000000 -0.000000000 6.005791907
Pt 0.000000000 -0.000000000 10.009653178
Pt 0.000000000 -0.000000000 14.013514450
Pt 1.415578728 1.415578728 -0.000000000
Pt 1.415578728 1.415578728 4.003861271
Pt 1.415578728 1.415578728 8.007722543
Pt 1.415578728 1.415578728 12.011583814
Pt 1.415578728 1.415578728 16.015445086

.....
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

Atomic positions for Pt(100) with 9 atomic planes:
$$$$$$$$$$$$$$$$$$$$$$$$$$$
b - For Pt(111) with 9 atomic planes:
 &system
    ibrav=  4,
A = 2.831157456,
C=36.0,
    nat=  9,
    ntyp= 1,
    ecutwfc =35.0,
    ecutrho = 350.0,
    occupations='smearing',
    smearing='marzari-vanderbilt',
    degauss=0.01,
 /
 &electrons
    mixing_beta = 0.7,
    conv_thr =  1.0d-8
electron_maxstep = 600,
 /
&ions
/
ATOMIC_SPECIES
Pt  195.084 Pt.pbe-nd-rrkjus.UPF
ATOMIC_POSITIONS {angstrom}
Pt 0.000000000 -0.000000000 -13.856406461
Pt 0.000000000 -0.000000000 -6.928203230
Pt 0.000000000 0.000000000 0.000000000
Pt 1.414213562 0.816496581 -16.165807537
Pt 1.414213562 0.816496581 -9.237604307
Pt 1.414213562 0.816496581 -2.309401077
Pt -0.000000000 1.632993162 -18.475208614
Pt -0.000000000 1.632993162 -11.547005384
Pt -0.000000000 1.632993162 -4.618802154

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Thanks in advance,
regards

R. Lelis-Sousa.
UFT/TO/Brazil.



-- 
Tenha uma ótima semana,

Atenciosamente,


Dra. Regina Lélis de Sousa
Professor Adjunto -- Universidade Federal do Tocantins
Campus de Araguaína
Rua Paraguai SN -- Esquina com a Urixamas
Telefone: +55(63)2112-2283
Caixa Postal 132
CEP: 77.838-824
Tocantins.
"Success is knowing that you have done your best and have exploited your
God-given or gene-given abilities to the next maximum extent. More than
this, no
one can do...".  Prof. Alan Graham MacDiarmid
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