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 <gautam...@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 <vh261...@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 <gautam...@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
>> > _______________________________________________
>> > Pw_forum mailing list
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>> > http://pwscf.org/mailman/listinfo/pw_forum
>>
>>
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