Dear Sir,
I have used this code but I didn't get the direct band gap structure
of monolayer WSe2.
&CONTROL
calculation='vc-relax',
outdir='monolayer WSe2',
prefix='calc',
pseudo_dir='/home/anindya/Desktop/pseudopotential',
verbosity='high',
disk_io='high',
wf_collect=.true.,
nstep = 50,
etot_conv_thr=1d-02,
forc_conv_thr=1d-02,
/
&SYSTEM
ibrav=4,
celldm(1)=6.2020811408d0, celldm(3)=4.3566118221d0,
nat=3,
ntyp=2,
ecutwfc=40.0d0,
ecutrho =130.0d0,
nbnd=200,
vdw_corr='Grimme-D2',
force_symmorphic=.true.,
input_dft='PBE',
occupations='fixed',
/
&ELECTRONS
diagonalization='david',
conv_thr=1d-08,
mixing_mode='plain',
mixing_beta=0.700d0,
/
&ions
ion_dynamics ='bfgs',
/
&cell
cell_dynamics ='bfgs',
cell_factor=15,
/
ATOMIC_SPECIES
Se 78.960000d0 Se_ONCV_PBE-1.0_r.oncvpsp.upf
W 183.840000d0 W_ONCV_PBE-1.1_r.oncvpsp.upf
ATOMIC_POSITIONS {alat}
W 0.5000000000d0 0.2886751346d0 2.1782995738d0
Se 0.5000000000d0 -0.2886751346d0 1.6692977456d0
Se 0.5000000000d0 -0.2886751346d0 2.6873014019d0
K_POINTS {automatic}
10 10 1 0 0 0
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.
On Wed, Mar 1, 2017 at 9:04 PM, Giovanni Cantele
<[email protected] <mailto:[email protected]>>
wrote:
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
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.
Giovanni
On 1 Mar 2017, at 16:17, Anindya Bose <[email protected]
<mailto:[email protected]>> wrote:
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.
On Wednesday, March 1, 2017, Giovanni Cantele
<[email protected]
<mailto:[email protected]>> wrote:
It is not clear how and to what extend your band structure
differs from shat you expect.
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
along your z direction should be large enough to prevent them
from interacting (otherwise, you are considering a periodic
crystal also along
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
to better describe inter-layer interaction, whereas you are
claiming that you want to study a system composed by a single
layer.
Also, I think that you don’t need to use the variable esm_bc
just to calculate the properties of a monolayer.
Giovanni
> On 1 Mar 2017, at 14:01, Anindya Bose <[email protected]>
wrote:
>
> Dear Sir,
>
> &CONTROL
> calculation='nscf',
> outdir='monolayer WSe2',
> prefix='calc',
> pseudo_dir='/home/anindya/Desktop/pseudopotentials',
> verbosity='low',
> disk_io='high',
> wf_collect=.true.,
> etot_conv_thr=1d-02,
> forc_conv_thr=1d-02,
> /
>
> &SYSTEM
> noncolin=.true.,
> lspinorb=.true.,
> ibrav=0,
> celldm(1)=6.2020811408d0, celldm(3)=4.3566118221d0,
> nat=3,
> ntyp=2,
> ecutwfc=40.0d0,
> nbnd=200,
> vdw_corr='Grimme-D2',
> starting_magnetization=0.05,
> force_symmorphic=.true.,
> input_dft='PBE',
> esm_bc='bc1',
> no_t_rev=.false.,
> /
>
> &ELECTRONS
> diagonalization='david',
> conv_thr=1d-08,
> mixing_mode='plain',
> mixing_beta=0.700d0,
> /
>
> &ions
> ion_dynamics ='bfgs',
> /
>
> &cell
> cell_dynamics ='bfgs',
> cell_factor=15,
> /
>
> ATOMIC_SPECIES
> Se 78.960000d0 Se_ONCV_PBE-1.0_nr.oncvpsp.upf
> W 183.840000d0 W_ONCV_PBE-1.1_nr.oncvpsp.upf
>
> CELL_PARAMETERS (alat= 6.20208114)
> 1.008112278 0.000000000 0.000000000
> -0.504056139 0.873050842 0.000000000
> 0.000000000 0.000000000 2.445357065
>
> ATOMIC_POSITIONS {alat}
> W 0.504056139 0.291016947 1.222674975
> Se 0.504056139 -0.291016947 0.699051439
> Se 0.504056139 -0.291016947 1.746298512
>
>
> K_POINTS {crystal_b}
> 4
> # Gamma-K-M-Gamma
> 0 0 0 20 !G
> 0.33 0.33 0 20 !K
> 0.5 0 0 20 !M
> 0 0 0 20 !G
>
> I am not getting the WSe2 monolayer band structure, can you
please help me in this regard.
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--
Giovanni Cantele, PhD
CNR-SPIN
c/o Dipartimento di Fisica
Universita' di Napoli "Federico II"
Complesso Universitario M. S. Angelo - Ed. 6
Via Cintia, I-80126, Napoli, Italy
e-mail: [email protected]
Phone: +39 081 676910
Skype contact: giocan74
ResearcherID: http://www.researcherid.com/rid/A-1951-2009
<http://www.researcherid.com/rid/A-1951-2009>
Web page: http://people.na.infn.it/~cantele
<http://people.na.infn.it/%7Ecantele>
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--
Giovanni Cantele, PhD
CNR-SPIN
c/o Dipartimento di Fisica
Universita' di Napoli "Federico II"
Complesso Universitario M. S. Angelo - Ed. 6
Via Cintia, I-80126, Napoli, Italy
e-mail: [email protected]
<mailto:[email protected]>
Phone: +39 081 676910
Skype contact: giocan74
ResearcherID: http://www.researcherid.com/rid/A-1951-2009
<http://www.researcherid.com/rid/A-1951-2009>
Web page: http://people.na.infn.it/~cantele
<http://people.na.infn.it/%7Ecantele>
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