<div dir="ltr">Thank you so much Vahid. I have a question though..how did you get the initial CELL_PARAMETERS ? I obtained the initial cell and atomic parameters from bulk.<br></div><div class="gmail_extra"><br clear="all"><div><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr">GAUTAM GADDEMANE<div>DEPARTMENT OF MATERIALS SCIENCE AND ENGINEERING</div><div>UNIVERSITY OF TEXAS AT DALLAS</div></div></div></div>
<br><div class="gmail_quote">On Thu, Oct 5, 2017 at 4:19 PM, Vahid Askarpour <span dir="ltr"><<a href="mailto:vh261281@dal.ca" target="_blank">vh261281@dal.ca</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi Gautam,<br>
<br>
The following relaxation input worked for me:<br>
<br>
BP<br>
2D<br>
&control<br>
    calculation='vc-relax'<br>
    restart_mode='from_scratch',<br>
    prefix='BP'<br>
    pseudo_dir='./'<br>
    verbosity='high'<br>
    tprnfor=.true.<br>
    tstress=.true.<br>
    etot_conv_thr=1.0e-06<br>
    forc_conv_thr=1.0e-05<br>
/<br>
&system<br>
    ibrav=0,<br>
    nat= 4, ntyp= 1<br>
    ecutwfc = 50, ecutrho=200,<br>
    occupations = 'fixed' ,<br>
/<br>
&electrons<br>
    diagonalization='cg'<br>
    conv_thr = 1.0e-12<br>
    mixing_beta = 0.7<br>
    electron_maxstep = 500<br>
    mixing_mode = 'plain'<br>
/<br>
&IONS<br>
  ion_dynamics = 'bfgs'<br>
  pot_extrapolation='atomic'<br>
  wfc_extrapolation='atomic'<br>
/<br>
&CELL<br>
  cell_dynamics = 'bfgs'<br>
  wmass=0.002<br>
  cell_factor=2.0<br>
  cell_dofree='xyz'<br>
/<br>
ATOMIC_SPECIES<br>
P  30.97376  P.pbesol-n-kjpaw_psl.0.1.UPF<br>
<br>
K_POINTS {automatic}<br>
14 12 1  0 0 0<br>
<br>
CELL_PARAMETERS (angstrom)<br>
   4.429539231   0.000000000   0.000000000<br>
   0.000000000   3.279402120   0.000000000<br>
   0.000000000   0.000000000  31.941846246<br>
<br>
ATOMIC_POSITIONS (crystal)<br>
P        0.001152971   0.000000000   0.015264978<br>
P        0.335395312   0.499999800   0.015264292<br>
P        0.501101273   0.499999800   0.081335135<br>
P        0.835350444   0.000000000   0.081335495<br>
<br>
Best,<br>
<br>
Vahid<br>
<span class="HOEnZb"><font color="#888888"><br>
Vahid Askarpour<br>
Department of Physics and Atmospheric Science<br>
Dalhousie University,<br>
Halifax, NS, Canada<br>
</font></span><div class="HOEnZb"><div class="h5"><br>
> On Oct 5, 2017, at 4:45 PM, Gautam Gaddemane <<a href="mailto:gautamg88@gmail.com">gautamg88@gmail.com</a>> wrote:<br>
><br>
> Dear All,<br>
><br>
> I am trying to calculate the bands tructure for monolayer phosphorene and I am just a week old in using quantum espresso.<br>
> 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.<br>
> I have attahced the file I used to relax in this email<br>
><br>
><br>
> &CONTROL<br>
>   calculation='vc-relax',<br>
>   outdir='./',<br>
>   prefix='calc',<br>
>   pseudo_dir='./',<br>
>   verbosity='high',<br>
> /<br>
><br>
> &SYSTEM<br>
>   ibrav=0,<br>
>   celldm(1)= 8.276999830d0<br>
>   nat=4,<br>
>   ntyp=1,<br>
>   ecutwfc=60,<br>
>   ecutrho=360,<br>
>   input_dft='lda',<br>
>   occupations='smearing',<br>
>   smearing='mv',<br>
>   degauss=0.005d0,<br>
> /<br>
><br>
> &ELECTRONS<br>
>   conv_thr=1d-06,<br>
>   mixing_beta=0.7d0,<br>
> /<br>
> &IONS<br>
>   ion_dynamics='bfgs'<br>
> /<br>
><br>
> &CELL<br>
>   cell_dynamics='bfgs'<br>
>   cell_dofree='2Dshape'<br>
> /<br>
> ATOMIC_SPECIES<br>
>   P 30.973800d0 P.pw-mt_fhi.UPF<br>
><br>
> ATOMIC_POSITIONS {crystal}<br>
><br>
>  P  0.090000004         0.000000000         0.050195117<br>
>  P  0.909999967         0.000000000         0.949804902<br>
>  P  0.590000033         0.500000000         0.949804902<br>
>  P  0.409999996         0.500000000         0.050195117<br>
><br>
> K_POINTS {automatic}<br>
><br>
>   12 12 1 0 0 0<br>
><br>
> CELL_PARAMETERS {alat}<br>
><br>
>      1.0000000000000000    0.0000000000000000    0.0000000000000000<br>
>      0.0000000000000000    0.7511415530000000    0.0000000000000000<br>
>      0.0000000000000000    0.0000000000000000   4.68036529200000000<br>
><br>
><br>
> thank you<br>
> Gautam<br>
><br>
> GAUTAM GADDEMANE<br>
> DEPARTMENT OF MATERIALS SCIENCE AND ENGINEERING<br>
> UNIVERSITY OF TEXAS AT DALLAS<br>
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