[Pw_forum] phosphorene monolayer

[Vahid Askarpour]

Hi Gautam,

The following relaxation input worked for me:

BP
2D
&control
    calculation='vc-relax'
    restart_mode='from_scratch',
    prefix='BP'
    pseudo_dir='./'
    verbosity='high'
    tprnfor=.true.
    tstress=.true.
    etot_conv_thr=1.0e-06
    forc_conv_thr=1.0e-05
/
&system
    ibrav=0,
    nat= 4, ntyp= 1
    ecutwfc = 50, ecutrho=200,
    occupations = 'fixed' , 
/
&electrons
    diagonalization='cg'
    conv_thr = 1.0e-12
    mixing_beta = 0.7
    electron_maxstep = 500
    mixing_mode = 'plain'
/
&IONS
  ion_dynamics = 'bfgs'
  pot_extrapolation='atomic'
  wfc_extrapolation='atomic'
/
&CELL
  cell_dynamics = 'bfgs'
  wmass=0.002
  cell_factor=2.0
  cell_dofree='xyz'
/
ATOMIC_SPECIES
P  30.97376  P.pbesol-n-kjpaw_psl.0.1.UPF 

K_POINTS {automatic}
14 12 1  0 0 0

CELL_PARAMETERS (angstrom)
   4.429539231   0.000000000   0.000000000
   0.000000000   3.279402120   0.000000000
   0.000000000   0.000000000  31.941846246

ATOMIC_POSITIONS (crystal)
P        0.001152971   0.000000000   0.015264978
P        0.335395312   0.499999800   0.015264292
P        0.501101273   0.499999800   0.081335135
P        0.835350444   0.000000000   0.081335495

Best,

Vahid

Vahid Askarpour
Department of Physics and Atmospheric Science
Dalhousie University,
Halifax, NS, Canada

> On Oct 5, 2017, at 4:45 PM, Gautam Gaddemane <gautamg88 at gmail.com> wrote:
> 
> Dear All,
> 
> I am trying to calculate the bands tructure for monolayer phosphorene and I am just a week old in using quantum espresso.
> From the bulk unit cell I prepared an input file to relax the structure but I was not able to get a good lattice constant nor a good band gap. It would be very helpful if someone would guide me in this procedure.
> I have attahced the file I used to relax in this email
> 
>  
> &CONTROL 
>   calculation='vc-relax', 
>   outdir='./', 
>   prefix='calc', 
>   pseudo_dir='./', 
>   verbosity='high', 
> / 
>  
> &SYSTEM 
>   ibrav=0,
>   celldm(1)= 8.276999830d0 
>   nat=4, 
>   ntyp=1, 
>   ecutwfc=60, 
>   ecutrho=360, 
>   input_dft='lda', 
>   occupations='smearing', 
>   smearing='mv', 
>   degauss=0.005d0, 
> / 
>  
> &ELECTRONS 
>   conv_thr=1d-06, 
>   mixing_beta=0.7d0, 
> / 
> &IONS 
>   ion_dynamics='bfgs' 
> / 
>  
> &CELL 
>   cell_dynamics='bfgs' 
>   cell_dofree='2Dshape'   
> / 
> ATOMIC_SPECIES 
>   P 30.973800d0 P.pw-mt_fhi.UPF 
>  
> ATOMIC_POSITIONS {crystal} 
>  
>  P  0.090000004         0.000000000         0.050195117
>  P  0.909999967         0.000000000         0.949804902
>  P  0.590000033         0.500000000         0.949804902
>  P  0.409999996         0.500000000         0.050195117 
>  
> K_POINTS {automatic} 
>  
>   12 12 1 0 0 0 
>  
> CELL_PARAMETERS {alat} 
>  
>      1.0000000000000000    0.0000000000000000    0.0000000000000000 
>      0.0000000000000000    0.7511415530000000    0.0000000000000000 
>      0.0000000000000000    0.0000000000000000   4.68036529200000000
> 
> 
> thank you
> Gautam
> 
> GAUTAM GADDEMANE
> DEPARTMENT OF MATERIALS SCIENCE AND ENGINEERING
> UNIVERSITY OF TEXAS AT DALLAS
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