[Pw_forum] Problem in surface relaxation of (1 1 2)

[LEUNG Clarence]

Dear QE users,


When I relax the surface of Co2P (1 1 2), it can not converge.


Before I relax the surface, I have vc-relax the Co2P unitcell and then cleave surface into (112).


In my calculation, the bottom two layer is fixed.


The following is my input file:


&CONTROL
  calculation='relax',
  outdir='*',
  prefix='*',
  pseudo_dir='SSSP_acc_PBE' ,
  verbosity='low',
  etot_conv_thr = 1.0D-5 ,
  forc_conv_thr = 1.0D-4 ,
  nstep = 200 ,
  tstress = .false. ,
  tprnfor = .false. ,
/

&SYSTEM
  ibrav=0,
  celldm(1)=16.4246424228d0,
  nat=63,
  ntyp=2,
  ecutwfc=55,
  ecutrho=440,
  input_dft='pbe',
  occupations='smearing',
  smearing='gaussian',
  degauss=0.02d0,
  nosym = .true. ,
  vdw_corr = 'DFT-D' ,
/

&ELECTRONS
  conv_thr=1d-07,
  mixing_beta=0.7d0,
  electron_maxstep = 1000 ,
/
&IONS
  ion_dynamics = 'bfgs',
  bfgs_ndim = 3 ,
/

ATOMIC_SPECIES
  Co 58.933200d0 Co_pbe_v1.2.uspp.F.UPF
  P 30.973800d0 P.pbe-n-rrkjus_psl.1.0.0.UPF

ATOMIC_POSITIONS {crystal}
  Co   0.1903007006d0   0.8264988975d0   0.0000730554d0 0 0 0
  Co   0.1566110217d0   0.3560172521d0   0.0062118574d0 0 0 0
   P   0.4440459492d0   0.8585689647d0   0.0067426493d0 0 0 0
   P   0.5751265964d0   0.4682543944d0   0.0295539425d0 0 0 0
  Co   0.8625515101d0   0.9708162548d0   0.0300868448d0 0 0 0
  Co   0.8288721279d0   0.5003202430d0   0.0362226591d0 0 0 0
  Co   0.5518926580d0   0.0382544344d0   0.0441118595d0 0 0 0
   P   0.1997178508d0   0.5726455675d0   0.0512641641d0 0 0 0
  Co   0.1185651840d0   0.0941063301d0   0.0557274048d0 0 0 0
  Co   0.4117967783d0   0.6610010716d0   0.0696394011d0 0 0 0
   P   0.3306374318d0   0.1824724856d0   0.0741048569d0 0 0 0
  Co   0.9784626235d0   0.7168621617d0   0.0812568585d0 0 0 0
  Co   0.7014915107d0   0.2547851045d0   0.0891437196d0 0 0 0
  Co   0.6678018319d0   0.7843034592d0   0.0952825216d0 0 0 0
   P   0.9552367594d0   0.2868551718d0   0.0958133135d0 0 0 0
   P   0.0863174066d0   0.8965406015d0   0.1186246067d0 0 0 0
  Co   0.3737423203d0   0.3991024619d0   0.1191575090d0 0 0 0
  Co   0.3400629380d0   0.9286064501d0   0.1252933232d0 0 0 0
  Co   0.0630834682d0   0.4665406415d0   0.1331825237d0 0 0 0
   P   0.7109086610d0   0.0009317746d0   0.1403348283d0 0 0 0
  Co   0.6297559941d0   0.5223925371d0   0.1447980689d0 0 0 0
  Co   0.9229875884d0   0.0892872786d0   0.1587100652d0 0 0 0
   P   0.8418282419d0   0.6107586927d0   0.1631755211d0 0 0 0
  Co   0.4896534336d0   0.1451483687d0   0.1703275227d0 0 0 0
  Co   0.2126823209d0   0.6830713116d0   0.1782143838d0 0 0 0
  Co   0.1789926420d0   0.2125896662d0   0.1843531858d0 0 0 0
   P   0.4664275695d0   0.7151413788d0   0.1848839776d0 0 0 0
   P   0.5975082167d0   0.3248268085d0   0.2076952709d0 1 1 1
  Co   0.8849331304d0   0.8273886689d0   0.2082281732d0 1 1 1
  Co   0.8512537482d0   0.3568926571d0   0.2143639874d0 1 1 1
  Co   0.5742742783d0   0.8948268485d0   0.2222531879d0 1 1 1
   P   0.2220994711d0   0.4292179816d0   0.2294054925d0 1 1 1
  Co   0.1409468043d0   0.9506787442d0   0.2338687331d0 1 1 1
  Co   0.4341783986d0   0.5175734857d0   0.2477807294d0 1 1 1
   P   0.3530190521d0   0.0390448997d0   0.2522461853d0 1 1 1
  Co   0.0008442438d0   0.5734345758d0   0.2593981868d0 1 1 1
  Co   0.7238731310d0   0.1113575186d0   0.2672850479d0 1 1 1
  Co   0.6901834522d0   0.6408758733d0   0.2734238499d0 1 1 1
   P   0.9776183797d0   0.1434275859d0   0.2739546418d0 1 1 1
   P   0.1086990269d0   0.7531130156d0   0.2967659351d0 1 1 1
  Co   0.3961239406d0   0.2556748760d0   0.2972988374d0 1 1 1
  Co   0.3624445583d0   0.7851788642d0   0.3034346516d0 1 1 1
  Co   0.0854650885d0   0.3231130556d0   0.3113238520d0 1 1 1
   P   0.7332902813d0   0.8575041887d0   0.3184761566d0 1 1 1
  Co   0.6521376144d0   0.3789649512d0   0.3229393973d0 1 1 1
  Co   0.9453692087d0   0.9458596927d0   0.3368513936d0 1 1 1
   P   0.8642098622d0   0.4673311068d0   0.3413168494d0 1 1 1
  Co   0.5120350539d0   0.0017207828d0   0.3484688510d0 1 1 1
  Co   0.2350639412d0   0.5396437257d0   0.3563557121d0 1 1 1
  Co   0.2013742623d0   0.0691620804d0   0.3624945141d0 1 1 1
   P   0.4888091898d0   0.5717137929d0   0.3630253060d0 1 1 1
   P   0.6198898370d0   0.1813992226d0   0.3858365992d0 1 1 1
  Co   0.9073147507d0   0.6839610830d0   0.3863695015d0 1 1 1
  Co   0.8736353685d0   0.2134650712d0   0.3925053158d0 1 1 1
  Co   0.5966558986d0   0.7513992626d0   0.4003945162d0 1 1 1
   P   0.2444810914d0   0.2857903957d0   0.4075468208d0 1 1 1
  Co   0.1633284246d0   0.8072511583d0   0.4120100615d0 1 1 1
  Co   0.4565600189d0   0.3741458998d0   0.4259220578d0 1 1 1
   P   0.3754006724d0   0.8956173138d0   0.4303875136d0 1 1 1
  Co   0.0232258641d0   0.4300069899d0   0.4375395152d0 1 1 1
  Co   0.7462547513d0   0.9679299328d0   0.4454263763d0 1 1 1
  Co   0.7125650725d0   0.4974482874d0   0.4515651783d0 1 1 1
   P   0.0000000000d0   0.0000000000d0   0.4520959702d0 1 1 1

K_POINTS {automatic}
  3 3 3 0 0 0

CELL_PARAMETERS {alat}
  1.000000000000d0  0.000000000000d0  0.000000000000d0
  0.156048225790d0  1.067246524267d0  0.000000000000d0
  0.000000000000d0  0.000000000000d0  2.099899204004d0

 Best regards,

Clarence

City University of Hong Kong
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