[Pw_forum] phosphorene monolayer

[Gautam Gaddemane]

Thank you Dario.

Sent from my iPhone

> On Oct 6, 2017, at 3:27 AM, dario rocca <roccad at gmail.com> wrote:
> 
> Dear Gautam,
> it is not a problem to start from the experimental bulk structure since the monolayer structure is not that different.
> You should visualize your input file with Xcrysden. You would see that you don't have the correct geometry to start with.
> Best,
> Dario
> 
>> On Thu, Oct 5, 2017 at 11:24 PM, Gautam Gaddemane <gautamg88 at gmail.com> wrote:
>> 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.
>> 
>> GAUTAM GADDEMANE
>> DEPARTMENT OF MATERIALS SCIENCE AND ENGINEERING
>> UNIVERSITY OF TEXAS AT DALLAS
>> 
>>> On Thu, Oct 5, 2017 at 4:19 PM, Vahid Askarpour <vh261281 at dal.ca> wrote:
>>> 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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