[Pw_forum] Problem with PDOS of ionic crystals

Alexander G. Kvashnin agkvashnin at gmail.com
Fri Apr 4 16:00:31 CEST 2014 

Dear Giovanni,

OK, now I see what you mean.
Thank you again for detailed explanation!


On 4 April 2014 17:04, Giovanni Cantele <giovanni.cantele at spin.cnr.it>wrote:

> it is not a matter of d orbitals, I mentioned them just as an example.
>
> You are not able to calculate the full PDOS if the state you're projecting
> possess (even partially) a character
> (s, p, d, ....) which is not included in the pseudo potential.
>
> The band structure / eigenvalues are instead correct (at DFT level of
> approximation), because they're calculated
> using plane waves as basis set, not atomic orbitals!
>
> Giovanni
>
>
>
> On 04 Apr 2014, at 13:30, Alexander G. Kvashnin <agkvashnin at gmail.com>
> wrote:
>
> Dear Giovanni,
>
> Thank you for your quick answer!
> As I understand correctly, I am not able to calculate correct PDOS while I
> have no d orbitals in the pseudo?
>
>  *--*
> *Sincerely yours,*
> *Alexander G. Kvashnin *
>
>
> *=====================================================PhD Student Moscow
> Institute of Physics and Technology          http://mipt.ru/
> <http://s.wisestamp.com/links?url=http%3A%2F%2Fmipt.ru%2F&sn=>*
> *141700, Institutsky lane 9, Dolgoprudny, Moscow Region, Russia*
>
>
>
>
>
> *Junior research scientistTechnological Institute for Superhard and Novel
> Carbon Materials                                http://www.tisnum.ru/
> <http://s.wisestamp.com/links?url=http%3A%2F%2Fwww.tisnum.ru%2F&sn=>
> <http://s.wisestamp.com/links?url=http%3A%2F%2Fwww.ntcstm.troitsk.ru%2F&sn=>142190,
> Central'naya St. 7a, Troitsk, Moscow Region,
> Russia=====================================================*
>
>
> On 4 April 2014 13:18, Giovanni Cantele <giovanni.cantele at spin.cnr.it>wrote:
>
>>
>> On 04 Apr 2014, at 10:43, Alexander G. Kvashnin <agkvashnin at gmail.com>
>> wrote:
>>
>> Dear QE users,
>>
>> I tried to calculate PDOS for simple cubic NaCl structure. I performed an
>> optimization vc-relax with 6x6x6 k-points, than I made scf calculations,
>> nscf calculations and after that I ran projwfc to plot PDOS.
>> My question is why when I plotted DOS_Na+DOS_Cl it differs from the total
>> DOS for whole system, specially in conduction band?
>>
>> Here is my nscf file and input file for projfwc:
>>
>>  &control
>>     calculation='nscf'
>>     restart_mode='restart',
>>     tstress = .true.
>>     tprnfor = .true.
>>     prefix='nacl',
>>     pseudo_dir = '.',
>>     outdir='.',
>>     nstep = 200
>>  /
>>  &system
>>                     nosym = .false.,
>>                      ibrav = 1,
>>                      nat = 4,
>>                      ntyp = 2,
>>                      ecutwfc = 30,
>>                      celldm(1) = 10.750047341391399,
>>                      occupations = 'tetrahedra',
>>  /
>>  &electrons
>>     conv_thr =  1.0d-8
>>     mixing_beta = 0.7
>>     electron_maxstep = 300
>>  /
>> ATOMIC_SPECIES
>>  Na    22.9897    Na.pbe-sp-van_ak.UPF
>>  Cl    35.4527    Cl.pbe-n-van.UPF
>> ATOMIC_POSITIONS  crystal
>> Na      -0.500000000  -0.500000000   0.000000000
>> Na      -0.500000000   0.000000000  -0.500000000
>> Cl      -0.500000000   0.000000000   0.000000000
>> Cl      -0.500000000  -0.500000000  -0.500000000
>> Cl       0.000000000  -0.500000000   0.000000000
>> Cl       0.000000000   0.000000000  -0.500000000
>> Na       0.000000000   0.000000000   0.000000000
>> Na       0.000000000  -0.500000000  -0.500000000
>> K_POINTS automatic
>>  6 6 6  0 0 0
>>
>>  &inputpp
>>     outdir='./'
>>     prefix='nacl'
>>     ngauss=1, degauss=0.02
>>     DeltaE=0.05
>>     Emin=-15.0, Emax=15.0,
>>     filpdos='nacl.k'
>>  /
>>
>>
>> Any suggestion are welcome!
>> Thank you in advance!
>>  *--*
>> *Sincerely yours,*
>> *Alexander G. Kvashnin *
>>
>>
>> *=====================================================PhD Student Moscow
>> Institute of Physics and Technology          http://mipt.ru/
>> <http://s.wisestamp.com/links?url=http%3A%2F%2Fmipt.ru%2F&sn=>*
>> *141700, Institutsky lane 9, Dolgoprudny, Moscow Region, Russia*
>>
>>
>>
>>
>>
>> *Junior research scientistTechnological Institute for Superhard and Novel
>> Carbon Materials                                http://www.tisnum.ru/
>> <http://s.wisestamp.com/links?url=http%3A%2F%2Fwww.tisnum.ru%2F&sn=>
>> <http://s.wisestamp.com/links?url=http%3A%2F%2Fwww.ntcstm.troitsk.ru%2F&sn=>142190,
>> Central'naya St. 7a, Troitsk, Moscow Region,
>> Russia=====================================================*
>>
>>
>>
>>
>> Dear Alexander,
>>
>> inside the pdos output file you should find, for EACH eigenvalue at EACH
>> k-point the decomposition of
>> the wave function, together with the sum of the square modulus of the
>> expansion coefficients.
>>
>> What you should notice is that, while for occupied states |psi|^2 =
>> 1.000, the coefficient square moduli do
>> not sum up to 1, as you move to high energy unoccupied states.
>>
>> Should the basis set used for the projection be orthogonal and complete,
>> that should not occur. However,
>> the code, as far as I remember, is only able to project onto the atomic
>> orbitals included in the pseudo potentials.
>>
>> Therefore, while the bands, even though unoccupied, are correctly (at DFT
>> level!) computed, the projection onto
>> the atomic orbitals might not be enough because would require atomic
>> orbitals (e.g. d states) not included
>> in the pseudo. The result is that the sum of the partial dos is LESS than
>> the (correct) total DOS.
>>
>> Giovanni
>>
>> --
>>
>> 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: giovanni.cantele at spin.cnr.it
>> Phone: +39 081 676910
>> Skype contact: giocan74
>>
>> ResearcherID: http://www.researcherid.com/rid/A-1951-2009
>> Web page: http://people.na.infn.it/~cantele
>>
>>
>> _______________________________________________
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>>
>
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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: giovanni.cantele at spin.cnr.it
> Phone: +39 081 676910
> Skype contact: giocan74
>
> ResearcherID: http://www.researcherid.com/rid/A-1951-2009
> Web page: http://people.na.infn.it/~cantele
>
>
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>



-- 
*Sincerely yours,*

*Alexander G. Kvashnin *


*=====================================================PhD Student Moscow
Institute of Physics and Technology          http://mipt.ru/
<http://s.wisestamp.com/links?url=http%3A%2F%2Fmipt.ru%2F&sn=>*
*141700, Institutsky lane 9, Dolgoprudny, Moscow Region, Russia*





*Junior research scientistTechnological Institute for Superhard and Novel
Carbon Materials                                http://www.tisnum.ru/
<http://s.wisestamp.com/links?url=http%3A%2F%2Fwww.tisnum.ru%2F&sn=>
<http://s.wisestamp.com/links?url=http%3A%2F%2Fwww.ntcstm.troitsk.ru%2F&sn=>142190,
Central'naya St. 7a, Troitsk, Moscow Region,
Russia=====================================================*
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