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<div class="moz-cite-prefix">Dear Anindya,<br>
<br>
please provide an affiliation.<br>
Hard to say why you don't get the correct band structure<br>
but let me give me a few advices:<br>
<br>
Before attempting to relax your unit cell you should test<br>
the convergence with respect to several parameters with<br>
the known experimental structure. For example<br>
convergence with respect to sampling of the BZ and<br>
number of plane wave (ecutwfc)...<br>
Why do you set ecutrho if you're using norm conserving<br>
pseudos? Do one needs to set it for optimized norm-<br>
conserving Vanderbilt pseudos? I think the standard<br>
value of 4 times ecutwfc is just fine.<br>
Additionally, you're using norm-conserving pseudos...<br>
I guess that ecutwfc=40 is just too small. This brings me<br>
back to first point: Check convergence!! And why do you<br>
need 200 bands? Are the pseudos all-electron ones?<br>
<br>
Regards<br>
<br>
Thomas<br>
<br>
On 03/06/2017 12:55 PM, Anindya Bose wrote:<br>
</div>
<blockquote
cite="mid:CAJXtw3whCHk4zVKeco__YSefyKv5O1_hVG7pQef0JuGzCwNheQ@mail.gmail.com"
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<div>Dear Sir,<br>
</div>
I have used this code but I didn't get the direct band gap
structure of monolayer WSe2.<br>
&CONTROL<br>
calculation='vc-relax',<br>
outdir='monolayer WSe2',<br>
prefix='calc',<br>
pseudo_dir='/home/anindya/Desktop/pseudopotential',<br>
verbosity='high',<br>
disk_io='high',<br>
wf_collect=.true.,<br>
nstep = 50,<br>
etot_conv_thr=1d-02,<br>
forc_conv_thr=1d-02,<br>
/<br>
<br>
&SYSTEM<br>
ibrav=4,<br>
celldm(1)=6.2020811408d0, celldm(3)=4.3566118221d0,<br>
nat=3,<br>
ntyp=2,<br>
ecutwfc=40.0d0,<br>
ecutrho =130.0d0,<br>
nbnd=200,<br>
vdw_corr='Grimme-D2',<br>
force_symmorphic=.true.,<br>
input_dft='PBE',<br>
occupations='fixed',<br>
/<br>
<br>
&ELECTRONS<br>
diagonalization='david',<br>
conv_thr=1d-08,<br>
mixing_mode='plain',<br>
mixing_beta=0.700d0,<br>
/<br>
<br>
&ions<br>
ion_dynamics ='bfgs',<br>
/<br>
<br>
&cell<br>
cell_dynamics ='bfgs',<br>
cell_factor=15,<br>
/<br>
<br>
ATOMIC_SPECIES<br>
Se 78.960000d0 Se_ONCV_PBE-1.0_r.oncvpsp.upf<br>
W 183.840000d0 W_ONCV_PBE-1.1_r.oncvpsp.upf<br>
<br>
ATOMIC_POSITIONS {alat}<br>
W 0.5000000000d0 0.2886751346d0 2.1782995738d0<br>
Se 0.5000000000d0 -0.2886751346d0 1.6692977456d0<br>
Se 0.5000000000d0 -0.2886751346d0 2.6873014019d0<br>
<br>
K_POINTS {automatic}<br>
10 10 1 0 0 0<br>
<br>
</div>
I have enclosed my output band structure with this mail.Can you
please help me in this regard.How can I get the correct band
diagram of monolayer WSe2(direct bandgap). I have used all the
codes for spin calculation and I got the spin orbit coupling but
didn't find perfect band diagram.I will be waiting for your
response.</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Wed, Mar 1, 2017 at 9:04 PM,
Giovanni Cantele <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:giovanni.cantele@spin.cnr.it" target="_blank">giovanni.cantele@spin.cnr.it</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div style="word-wrap:break-word">I never use ism, maybe you
can read relevant papers in the literature. However, if
your purpose is just to simulate an isolated monolayer,
just add to the lattice vector orthogonal to the monolayer
<div>plane (a3, in your case) vacuum space, so if the
current length is, just to make an example, 5 A, try to
use 15 A. This is the so called supercell approach,
discussed several times in the forum.</div>
<span class="HOEnZb"><font color="#888888">
<div><br>
</div>
<div>Giovanni</div>
</font></span>
<div>
<div class="h5">
<div><br>
<div>
<blockquote type="cite">
<div>On 1 Mar 2017, at 16:17, Anindya Bose <<a
moz-do-not-send="true"
href="mailto:anindya@iiita.ac.in"
target="_blank">anindya@iiita.ac.in</a>>
wrote:</div>
<br
class="m_-4350864146537980139Apple-interchange-newline">
<div>Actually I have used esm_bc to add vacuum
in the structure.How can I add vacuum in this
monolayer WSE2 structure using quantum
espresso.Which code should be used.<br>
<br>
On Wednesday, March 1, 2017, Giovanni Cantele
<<a moz-do-not-send="true"
href="mailto:giovanni.cantele@spin.cnr.it"
target="_blank">giovanni.cantele@spin.cnr.it</a>>
wrote:<br>
<blockquote class="gmail_quote"
style="margin:0 0 0 .8ex;border-left:1px
#ccc solid;padding-left:1ex">It is not clear
how and to what extend your band structure
differs from shat you expect.<br>
However, one issue I can see is that if you
want to study MONOLAYER WSe2, you should be
aware of the fact that the vacuum space,
separating the periodic replicas<br>
along your z direction should be large
enough to prevent them from interacting
(otherwise, you are considering a periodic
crystal also along<br>
that direction). Currently, as far as I can
see such vacuum is < 5A, definitely too
small to simulate a monolayer. Additionally,
you also include vdw_corr, usually
introduced<br>
to better describe inter-layer interaction,
whereas you are claiming that you want to
study a system composed by a single layer.<br>
Also, I think that you don’t need to use the
variable esm_bc just to calculate the
properties of a monolayer.<br>
<br>
Giovanni<br>
<br>
<br>
<br>
<br>
> On 1 Mar 2017, at 14:01, Anindya Bose
<<a moz-do-not-send="true">anindya@iiita.ac.in</a>>
wrote:<br>
><br>
> Dear Sir,<br>
><br>
> &CONTROL<br>
> calculation='nscf',<br>
> outdir='monolayer WSe2',<br>
> prefix='calc',<br>
> pseudo_dir='/home/anindya/Des<wbr>ktop/pseudopotentials',<br>
> verbosity='low',<br>
> disk_io='high',<br>
> wf_collect=.true.,<br>
> etot_conv_thr=1d-02,<br>
> forc_conv_thr=1d-02,<br>
> /<br>
><br>
> &SYSTEM<br>
> noncolin=.true.,<br>
> lspinorb=.true.,<br>
> ibrav=0,<br>
> celldm(1)=6.2020811408d0,
celldm(3)=4.3566118221d0,<br>
> nat=3,<br>
> ntyp=2,<br>
> ecutwfc=40.0d0,<br>
> nbnd=200,<br>
> vdw_corr='Grimme-D2',<br>
> starting_magnetization=0.05,<br>
> force_symmorphic=.true.,<br>
> input_dft='PBE',<br>
> esm_bc='bc1',<br>
> no_t_rev=.false.,<br>
> /<br>
><br>
> &ELECTRONS<br>
> diagonalization='david',<br>
> conv_thr=1d-08,<br>
> mixing_mode='plain',<br>
> mixing_beta=0.700d0,<br>
> /<br>
><br>
> &ions<br>
> ion_dynamics ='bfgs',<br>
> /<br>
><br>
> &cell<br>
> cell_dynamics ='bfgs',<br>
> cell_factor=15,<br>
> /<br>
><br>
> ATOMIC_SPECIES<br>
> Se 78.960000d0
Se_ONCV_PBE-1.0_nr.oncvpsp.upf<br>
> W 183.840000d0
W_ONCV_PBE-1.1_nr.oncvpsp.upf<br>
><br>
> CELL_PARAMETERS (alat= 6.20208114)<br>
> 1.008112278 0.000000000
0.000000000<br>
> -0.504056139 0.873050842
0.000000000<br>
> 0.000000000 0.000000000
2.445357065<br>
><br>
> ATOMIC_POSITIONS {alat}<br>
> W 0.504056139 0.291016947
1.222674975<br>
> Se 0.504056139 -0.291016947
0.699051439<br>
> Se 0.504056139 -0.291016947
1.746298512<br>
><br>
><br>
> K_POINTS {crystal_b}<br>
> 4<br>
> # Gamma-K-M-Gamma<br>
> 0 0 0 20 !G<br>
> 0.33 0.33 0 20 !K<br>
> 0.5 0 0 20 !M<br>
> 0 0 0 20 !G<br>
><br>
> I am not getting the WSe2 monolayer
band structure, can you please help me in
this regard.<br>
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<br>
--<br>
<br>
Giovanni Cantele, PhD<br>
CNR-SPIN<br>
c/o Dipartimento di Fisica<br>
Universita' di Napoli "Federico II"<br>
Complesso Universitario M. S. Angelo - Ed. 6<br>
Via Cintia, I-80126, Napoli, Italy<br>
e-mail: <a moz-do-not-send="true">giovanni.cantele@spin.cnr.it</a><br>
Phone: +39 081 676910<br>
Skype contact: giocan74<br>
<br>
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Web page: <a moz-do-not-send="true"
href="http://people.na.infn.it/%7Ecantele"
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-- <br>
<br>
Giovanni Cantele, PhD<br>
CNR-SPIN<br>
c/o Dipartimento di Fisica<br>
Universita' di Napoli "Federico II"<br>
Complesso Universitario M. S. Angelo - Ed. 6<br>
Via Cintia, I-80126, Napoli, Italy<br>
e-mail: <a moz-do-not-send="true"
href="mailto:giovanni.cantele@spin.cnr.it"
target="_blank">giovanni.cantele@spin.cnr.it</a><br>
Phone: +39 081 676910<br>
Skype contact: giocan74<br>
<br>
ResearcherID: <a moz-do-not-send="true"
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<pre class="moz-signature" cols="72">--
Dr. rer. nat. Thomas Brumme
Max Planck Institute for the Structure and Dynamics of Matter
Luruper Chaussee 149
22761 Hamburg
Tel: +49 (0)40 8998 6557
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