<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>Thank you Dario.<br><br>Sent from my iPhone</div><div><br>On Oct 6, 2017, at 3:27 AM, dario rocca <<a href="mailto:roccad@gmail.com">roccad@gmail.com</a>> wrote:<br><br></div><blockquote type="cite"><div><div dir="ltr"><div><div><div><div>Dear Gautam,<br></div>it is not a problem to start from the experimental bulk structure since the monolayer structure is not that different.<br></div>You should visualize your input file with Xcrysden. You would see that you don't have the correct geometry to start with.<br></div>Best,<br></div>Dario<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Oct 5, 2017 at 11:24 PM, Gautam Gaddemane <span dir="ltr"><<a href="mailto:gautamg88@gmail.com" target="_blank">gautamg88@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><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"><span class=""><br clear="all"><div><div class="m_6222104544633623476gmail_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></span><div><div class="h5"><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="m_6222104544633623476HOEnZb"><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="m_6222104544633623476HOEnZb"><div class="m_6222104544633623476h5"><br>
> On Oct 5, 2017, at 4:45 PM, Gautam Gaddemane <<a href="mailto:gautamg88@gmail.com" target="_blank">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 <a href="http://P.pw">P.pw</a>-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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