Dear Neel Singh,
your input specifies ibrav=1 (that is Simple Cubic): only the value of a is
taken in consideration while b and c are discarded. If you want an orthorombic
structure the proper ibrav is another one. (ibrav=6 if I remember
correctly, but please check).
have you tried to visualize your structure by xcrysdens to check it is ok?
is the system magnetic ? if so you need to specify some starting
magnetization.
best regrads,
stefano de Gironcoli - SISSA and DEMOCRITOS
Quoting Neel Singh <neelphysics at yahoo.in>:
> Hi sir,
>
> ?Sir i have calculated the band structure of YVO4? and it is coming
> as near about 0.5 ev .. sir as suggested by you in earlier reply that
>
>> means band gap at gamma = 0.3058-(-8.9833)=? 8.2891
>> ? which is very large ??
>
> Not necessarily, the offset of band in a periodic system is arbitrary. You?
> need to know where you Fermi energy is, or which are the HOMO and LUMO of?
> your system to find the gap.
>
> I have calculated Fermi energy and it is coming as 6.108. The band
> gap of YVO4 is 3.9 eV experimental and DFT calculates the band gap
> as nearly half i..e. it should come as 1.8 eV approx. Please help..
> Thanks In advance.My Input files are listed below...
>
> SCF INPUT
> ===============================================
>
> ?&control
> ??? calculation='scf',
> ??? restart_mode='from_scratch',
> ??? prefix='yvo'
> ??? pseudo_dir = '/home/physics/pseudo/',
> ??? outdir='/home/physics/work/yvo/temp'
> ?/
> ?&system
> ??? ibrav =1, a=7.118300514, b= 7.118300514, c=6.289300454
> , nat =24, ntyp= 3,? ecutwfc = 40.0,ecutrho=300,
> ?occupations='smearing', smearing='mp', degauss=0.01,
>
>
> ?/
> ?&electrons
> ??? mixing_beta = 0.7
> ??? diagonalization = 'david'
> ??? conv_thr =? 1.0e-6
> /
> ?&ions
> ?/
>
> ATOMIC_SPECIES
> ? Y???? 88.90585???? Y.pbe-nsp-van.UPF
> ? V???? 50.9415????? V.pbe-sp-van.UPF
> ? O???? 15.9994????? O.pbe-van_ak.UPF
> ATOMIC_POSITIONS {angstrom}
> Y???????????? 0.000000000?? 5.338725356??? 0.786162553
> /
> /
>
> K_POINTS {automatic}
> ? 4 4 4 0 0 0
> =======================================================
> ?????????????????????????????? Bands Input
> ======================================================
>
>
> ?&control
> ??? calculation='bands'
> ??? pseudo_dir = '/home/physics/pseudo/',
> ??? outdir='/home/physics/work/yvo/temp',
> ??? prefix='yvo',
> ?
> ?/
> ?&system
> ??? ibrav =1, a=7.118300514, b= 7.118300514, c=6.289300454, nat=24, ntyp=3,
> ecutwfc = 40.0,ecutrho=300, occupations='smearing', smearing='mp',
> degauss=0.01, nbnd= 115,
> ???
> ?/
> ?&electrons
> ?? mixing_beta=0.7
> ?? conv_thr=1.0e-6
> ?diagonalization = 'david'
> /
> &ions
> ?/
>
> ATOMIC_SPECIES
> ?Y?????? 88.90585???? Y.pbe-nsp-van.UPF
> ? V????? 50.9415????? V.pbe-sp-van.UPF
> ? O???? 15.9994????? O.pbe-van_ak.UPF
> ATOMIC_POSITIONS {angstrom}
> Y???????????? 0.000000000?? 5.338725356??? 0.786162553
> \
> \
> K_POINTS
> ?26
> 0.000 0.000 0.000? 1
> 0.000 0.000 0.125? 1
> 0.000 0.000 0.250? 1
> 0.000 0.000 0.375? 1
> 0.000 0.000 0.500? 1????????????????????????????
> 0.125 0.125 0.500? 1????????????????????????????
> 0.250 0.250 0.500? 1????????????????????????????
> 0.375 0.375 0.500? 1???????????????????????????
> 0.500 0.500 0.500? 1????????????????????????????
> 0.500 0.500 0.333? 1????????????????????????????
> 0.500 0.500 0.166? 1????????????????????????????
> 0.500 0.500 0.000? 1????????????????????????????
> 0.375 0.375 0.000? 1????????????????????????????
> 0.250 0.250 0.000? 1????????????????????????????
> 0.125 0.125 0.000? 1????????????????????????????
> 0.000 0.000 0.000? 1????????????????????????????
> 0.000 0.000 0.166? 1???????????????????????????
> 0.000 0.000 0.333? 1????????????????????????????
> 0.000 0.166 0.500? 1??????????????????????????
> 0.000 0.333 0.500? 1???????????????????????????
> 0.000 0.500 0.500? 1????????????????????????????
> 0.000 0.500 0.333? 1????????????????????????????
> 0.000 0.500 0.166? 1????????????????????????????
> 0.000 0.500 0.000? 1????????????????????????????
> 0.000 0.333 0.000? 1????????????????????????????
> 0.000 0.166 0.000? 1
> ============================================================
> ===========================================================
> ?&inputpp
> ??? prefix? = 'yvo'
> ??? outdir = '/home/physics/work/yvo/temp'
> ??? filband = 'yvobands.dat'
> /
> ========================================
> Plotband INPUTS
> =======================================
> yvobands.dat
> -10? 12
> yvobands.xmgr
> yvobands.ps
> 6.1088
> 1.0? 0.00
> ================================================
> ============================================
>
> With regards,
> Neel Singh
> Univeristy of Delhi
> --- On Tue, 28/7/09, Lorenzo Paulatto <paulatto at sissa.it> wrote:
>
> From: Lorenzo Paulatto <paulatto at sissa.it>
> Subject: Re: [Pw_forum] Not getting right Band structure
> To: "PWSCF Forum" <pw_forum at pwscf.org>
> Date: Tuesday, 28 July, 2009, 10:07 AM
>
> In data 28 luglio 2009 alle ore 11:54:14, Neel Singh?
> <neelphysics at yahoo.in> ha scritto:
>> means band gap at gamma = 0.3058-(-8.9833)=? 8.2891
>> ? which is very large ??
>
> Not necessarily, the offset of band in a periodic system is arbitrary. You?
> need to know where you Fermi energy is, or which are the HOMO and LUMO of?
> your system to find the gap.
>
>
>> 2) In the output of SCF and Bands , the output file has 4 warnings
>
> This a very frequently asked question, please see the corresponing entry?
> in the manual:
> http://www.pwscf.org/guide/2.1.2/html-node/node56.html
> http://www.pwscf.org/guide/2.1.2/html-node/node57.html
>
>
>> for this I have already increase the following quantities? in the???
>> increments
>> kinetic-energy cutoff? ???=? ? ? 40.0000? Ry to 60
>> ? ? ? charge density cutoff? ???=? ???250.0000? Ry to 400
>> But still the warnings are there.
>
> It is not a big increment of the cutoff that will solve this problem, but?
> a small increment or nr1, nr2 nr3
>
> cheers, and good work
>
> --
> Lorenzo Paulatto
> SISSA? &? DEMOCRITOS (Trieste)
> phone: +39 040 3787 511
> skype: paulatz
> www:???http://people.sissa.it/~paulatto/
>
> ? ???*** save italian brains ***
> ? http://saveitalianbrains.wordpress.com/
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