[QE-users] Getting convergence on a cell obtained from a cif using vc-relax

Reinaldo Pis Diez reinaldo.pisdiez at gmail.com
Sat Jun 2 16:04:34 CEST 2018


Dear Arles,

Thanks for your answer. I'm using the GBRV pseudopotentials family, 
in which the authors indicate that "In particular, the GBRV 
potentials are designed to run at a plane-wave cutoff of 40 Ry and a 
charge-density cutoff of 200 Ry..." [Comp Mat Sci 81 (2104) 446). I 
agree that the systems tested by the authors do not include TM 
complexes, so, probably, I cannot expect a good transferability for 
PS, so this could be the error's source. I'll investigate this issue.

Regards,

Reinaldo

On 01/06/18 11:47, Arles V. Gil Rebaza wrote:
> Dear Reinaldo, are you sure that these values of ecutwfc =  40 
> and  ecutrho  = 200 describe your system well? Probabily you 
> should increase these values, in order to describe the transition 
> metal atom (Cu) and the total energy (forces and pressure depends 
> of the  total energy). Try to converge the total energy of the 
> system respect to ecutwfc value performing self-consistent 
> calculation for different vaues of ecutwfc. Furthermore, for US 
> pseudopotential the ecutrho value is tipically 8 to 12 times 
> ecutwfc (see QE manual).
>
> Best
>
> Dr. Arles V. Gil Rebaza
> Instituto de Física La Plata
> La Plata - Argentina.
>
> 2018-06-01 11:20 GMT-03:00 Reinaldo Pis Diez 
> <reinaldo.pisdiez at gmail.com <mailto:reinaldo.pisdiez at gmail.com>>:
>
>     Dear folks,
>
>     I usually help some experimentalist fellows from the Center I
>     belong by calculating geometries, cell parameters, vibrational
>     frequencies, electronic transitions, etc, of transition metal
>     complexes. As the cif file is often available, I use it to
>     create the input file for PWScf using Virtual Nano Lab from
>     Quantum Wise.
>
>     Although convergence of the vc-relax job is usually achieved,
>     some cases are more problematic. Job ends with a high pressure
>     and with atomic forces far from thresholds when 'bfgs' is used
>     both for &ions and &cell namelists. Using 'damp' does not help
>     to get geometry and cell parameters optimized. Thus my (very
>     general) question is: does anybody know an strategy to
>     systematically get convergence when doing vc-relax? A link to
>     a tutorial or a document is welcome.
>
>     For completeness, the input of one of the problematic cases is
>     appended below. By the way, I'm using "Program PWSCF v.6.1
>     (gpu tag v1.0)" compiled with PGI compilers and MKL libraries
>     on a CentOS box with a Titan X (Pascal) gpu.
>
>     Thanks in advance
>
>     Reinaldo
>     Center of Inorganic Chemistry
>     Natl Univ of La Plata, Argentina
>
>     Input follows....
>
>     &CONTROL
>      title         = 'Cu-ovatpnh2'
>      calculation   = 'vc-relax'
>      restart_mode  = 'from_scratch'
>      outdir        = './'
>      pseudo_dir    = './'
>      prefix        = 'Cu-ovatpnh2'
>      etot_conv_thr = 0.0001
>      forc_conv_thr = 0.0004
>      tstress       = .true.
>      tprnfor       = .true.
>      nstep         = 200
>     /
>
>     &SYSTEM
>       ibrav       = 14
>       celldm(1)   = 9.9320792573d0
>       celldm(2)   = 2.0161515879d0
>       celldm(3)   = 2.1156030541d0
>       celldm(4)   = -0.1705259449d0
>       celldm(5)   = -0.0219091103d0
>       celldm(6)   = -0.2238523262d0
>       nat         =  59
>       ntyp        =   6
>       ecutwfc     =  40
>       ecutrho     = 200
>       input_dft   = 'pbe'
>       occupations = 'smearing'
>       smearing    = 'mv'
>       degauss     = 0.005
>       nspin       = 2
>       starting_magnetization(1) = 0.7
>     /
>
>     &ELECTRONS
>       conv_thr        = 1d-06
>       mixing_beta     = 0.6
>       mixing_mode     = 'plain'
>       mixing_ndim     = 8
>       diagonalization = 'david'
>     /
>
>     &IONS
>      ion_dynamics = 'bfgs'
>     /
>
>     &CELL
>      cell_dynamics = 'bfgs'
>      press         = 0.5
>     /
>
>     ATOMIC_SPECIES
>       Cu 63.546000d0 cu_pbe_v1.2.uspp.F.UPF
>       C  12.010700d0  c_pbe_v1.2.uspp.F.UPF
>       H   1.007940d0  h_pbe_v1.4.uspp.F.UPF
>       N  14.006700d0  n_pbe_v1.2.uspp.F.UPF
>       O  15.999400d0  o_pbe_v1.2.uspp.F.UPF
>       S  32.065000d0  s_pbe_v1.4.uspp.F.UPF
>
>     ATOMIC_POSITIONS (crystal)
>     C        0.082231085   0.204570350   0.616545553
>     C        0.917768915   0.795429650   0.383454447
>     C        0.172973917   0.203448044   0.733466608
>     C        0.827026083   0.796551956   0.266533392
>     H        0.367673209   0.258122966   0.770942028
>     H        0.632326791   0.741877034   0.229057972
>     C        0.987334077   0.125087827   0.797766960
>     C        0.012665923   0.874912173   0.202233040
>     H        1.019591574   0.112838755   0.892010655
>     H       -0.019591574   0.887161245   0.107989345
>     C        0.756454381   0.067986708   0.729401520
>     C        0.243545619   0.932013292   0.270598480
>     H        0.580696185   0.004985342   0.755622580
>     H        0.419303815   0.995014658   0.244377420
>     C        0.224564542   0.266351629   0.518206870
>     C        0.775435458   0.733648371   0.481793130
>     H        0.388829444   0.346391746   0.560989945
>     H        0.611170556   0.653608254   0.439010055
>     H        0.304022379   0.192372172   0.457292153
>     H        0.695977621   0.807627828   0.542707847
>     C        0.956901991   0.245893003   0.340167231
>     C        0.043098009   0.754106997   0.659832769
>     H        0.022416710   0.153595990   0.313033710
>     H        0.977583290   0.846404010   0.686966290
>     C        0.771131988   0.269306261   0.255617666
>     C        0.228868012   0.730693739   0.744382334
>     C        0.652850645   0.378765293   0.282708985
>     C        0.347149355   0.621234707   0.717291015
>     C        0.462994923   0.392175655   0.192940332
>     C        0.537005077   0.607824345   0.807059668
>     C        0.403148927   0.302768506   0.084001267
>     C        0.596851073   0.697231494   0.915998733
>     H        0.259814627   0.314740185   0.016757517
>     H        0.740185373   0.685259815   0.983242483
>     C        0.525750373   0.196269824   0.058490144
>     C        0.474249627   0.803730176   0.941509856
>     H        0.478830729   0.128376775   0.971151210
>     H        0.521169271   0.871623225   0.028848790
>     C        0.705969389   0.179966480   0.142934709
>     C        0.294030611   0.820033520   0.857065291
>     H        0.804698818   0.098652977   0.124221693
>     H        0.195301182   0.901347023   0.875778307
>     C        0.184454672   0.523754793   0.135830920
>     C        0.815545328   0.476245207   0.864169080
>     H        0.287576875   0.544363666   0.053314825
>     H        0.712423125   0.455636334   0.946685175
>     H        0.118308380   0.611071476   0.178999457
>     H        0.881691620   0.388928524   0.821000543
>     H        0.013394359   0.440437861   0.110093147
>     H        0.986605641   0.559562139   0.889906853
>     N        0.053284394   0.319764373   0.444382321
>     N        0.946715606   0.680235627   0.555617679
>     O        0.705759527   0.466685324   0.381694456
>     O        0.294240473   0.533314676   0.618305544
>     O        0.356827705   0.498376849   0.225196110
>     O        0.643172295   0.501623151   0.774803890
>     S        0.766003561   0.110202377   0.587178900
>     S        0.233996439   0.889797623   0.412821100
>     Cu      -0.000000000   0.500000000   0.500000000
>
>     K_POINTS {automatic}
>       3 3 3 0 0 0
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>
> -- 
> Arles V.
>
>
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