[Pw_forum] Saw-like E-field

[Jaret Qi]

Hello QE users,I have an interface between semiconductor and semi-metallic. The system along z-direction is 30 A in length, I need to apply a saw-like electric field along that direction. So the z-direction enlarged by extra 15 A as vacuum and I added 2Dxy to fix the whole system along the z-direction. I noticed atoms are moving apart along the z-direction which will end up with wrong bond length, I think something wrong is going there. 
What do you suggest?  
see my input:&control    calculation  = 'vc-relax'    restart_mode = 'restart'    pseudo_dir   = './'    outdir       = './'    prefix       = 'interface'    nstep = 100 ,
  / &system    ibrav=0    celldm(1)=7.540006694    nat=40    ntyp=7    ecutwfc = 30 ,    ecutrho=300    occupations='smearing'    degauss=0.02    nspin=2    starting_magnetization(3) = 1     lda_plus_u = .true.    Hubbard_U(3)= 2    Hubbard_J0(3)=0.7
 / &electrons    mixing_beta=0.3,
    electron_maxstep=500/&IONS
/&CELLcell_dofree=2Dxy
/

ATOMIC_SPECIES  Sr    87.62      Sr.pbe-nsp-van.UPF  La   138.90547   La.pbe-nsp-van.UPF  Mn   54.938050   Mn.pbe-sp-van.UPF  O    15.999400    O.pbe-n-rrkjus_psl.0.1.UPF  Ti    47.867    Ti.pbe-sp-van_ak.UPF  Pb   207.2      Pb.pbe-dn-rrkjus_psl.0.2.2.UPF  Zr    91.224    Zr.pbe-nsp-van.UPFATOMIC_POSITIONS (alat)Sr      -0.004286582  -0.004286582   0.035485489Mn       0.469832598   0.469832598   0.500200985O        0.468718134   0.468718134   0.057137164O        0.470466092  -0.002158378   0.540978401O       -0.002158378   0.470466092   0.540978401La      -0.002379194  -0.002379194   0.954657048Mn       0.470294487   0.470294487   1.429859548O        0.470511082   0.470511082   0.968221597O        0.470759352  -0.001863403   1.435355937O       -0.001863403   0.470759352   1.435355937La      -0.002468250  -0.002468250   1.896245497Mn       0.469593986   0.469593986   2.358835338O        0.469937641   0.469937641   1.891788856O        0.470392988  -0.002367132   2.328749493O       -0.002367132   0.470392988   2.328749493Pb      -0.005746777  -0.005746777   2.810974333........... 

K_POINTS {automatic}  6 6 1 0 0 0
CELL_PARAMETERS alat   0.944618208  -0.000071177  -0.000242520  -0.000071177   0.944618208  -0.000242520  -0.002160529  -0.002160529  11.613149660


Best!JaretASU
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