[Pw_forum] DFT+U and starting_ns_eigenvalue(m,ispin,I)

Matteo Cococcioni matteo at umn.edu
Wed Mar 25 15:13:27 CET 2015


Dear Wajood,

to be precise: the starting_ns_eigenvalue flag allows you to change the
eigenvalue keeping the eigenvector fixed at what it was after the first
iteration (i.e., when the first non trivial occupation matrix is obtained).
But I still do not understand what you want to do. What is the difference
between "filling of d levels" and "eigenvalues of the occupation matrix"?
What do you mean exactly for "d levels"? If you mean Kohn-Sham states yes,
you can change their occupations (there is a card to do that, after you
choose occupations = 'from_input" if I'm not wrong) but they are not going
to be purely d states (i.e. they are not going to correspond exactly to
Bloch sums of atomic d states). Maybe some will but it all depends on the
electronic structure of the system.

Matteo

On Wed, Mar 25, 2015 at 2:53 PM, Wajood A Diery <wdiery at mit.edu> wrote:

>  Dear Matteo,
> I dont think this is what am doing. As far as I understand, starting_ns_eigenvalue(m,ispin,I)
> overwrites the mth eigenvalue not the occupation matrix it self. My
> question was if i can define the occupation matrix that corresponds to
> different filling of the d levels.
> Best
> Wajood
>
>  ------------------------------
> *From:* pw_forum-bounces at pwscf.org [pw_forum-bounces at pwscf.org] on behalf
> of Matteo Cococcioni [matteo at umn.edu]
> *Sent:* 25 March 2015 09:24
> *To:* PWSCF Forum
> *Subject:* Re: [Pw_forum] DFT+U and starting_ns_eigenvalue(m,ispin,I)
>
>    Dear Wajood,
>
>  isn't this what you are already doing?
>
>  Matteo
>
> On Wed, Mar 25, 2015 at 11:33 AM, Wajood A Diery <wdiery at mit.edu> wrote:
>
>>  Thank you so much.  One more question: is there a way in quantum
>> espresso to control the occupation matrix where the user can define the
>> occupation of the orbital in the occupation matrix?
>> Best
>> Wajood
>>  ------------------------------
>> *From:* pw_forum-bounces at pwscf.org [pw_forum-bounces at pwscf.org] on
>> behalf of Matteo Cococcioni [matteo at umn.edu]
>> *Sent:* 24 March 2015 13:56
>> *To:* PWSCF Forum
>> *Subject:* Re: [Pw_forum] DFT+U and starting_ns_eigenvalue(m,ispin,I)
>>
>>    Dear Wajood,
>>
>>  it is not a problem. the eigenvalues are printed in growing order. the
>> important thing is that you get the xz state corresponding to the 0
>> eigenvalue. and it seems to be the case (although it is not a pure xz and
>> has a component on z^2)
>>
>>  regards,
>>
>>  Matteo
>>
>> On Tue, Mar 24, 2015 at 6:30 PM, Wajood A Diery <wdiery at mit.edu> wrote:
>>
>>>  Dear Pwscf users,
>>> I have few questions about starting_ns_eigenvalue(m,ispin,I) and the
>>> occupation matrix for DFT+U. Am trying to fix the occupation of the d
>>> orbitals in Mn in BiMnO3. I've used starting_ns_eigenvalue(m,ispin,I) to
>>> specify the following occupation: 4 electrons in dz2, dyz, dx2-y2 and dxy
>>> and zero occupation for dxz. I was expecting to get eigenvalues such as
>>> 1.000  0.000  1.000  1.000  1.000, which give the occupation of the
>>> d-orbital,  but I got  0.000  1.000  1.000  1.000  1.000?  i've tried
>>> different occupations of the d-orbital and I always  get the same
>>> occupation or eigenvalues : 0.000  1.000  1.000  1.000  1.000? I am not
>>> sure if I miss understand the statring_ns_eigenvalue tag or there is
>>> something else that am missing? any help or suggestion will  be
>>> appreciated.
>>> Wajood
>>> Mechanical Engineering Department
>>> MIT
>>> This is the part of the input file related to my Question
>>> &system
>>>     ibrav = 0,
>>>      celldm(1)= 18.013436
>>>     nat = 40,
>>>     ntyp = 3,
>>>     ecutwfc = 60,
>>>     nspin = 2,
>>>     starting_magnetization(2)=1,
>>>    occupations='smearing', smearing='gauss',
>>>     degauss=0.01
>>>    lda_plus_u=.true.
>>>    lda_plus_u_kind=1
>>>      Hubbard_U(2)=8
>>>     Hubbard_J(1,2)=1.06
>>> starting_ns_eigenvalue(1,1,2)=1.0,
>>> starting_ns_eigenvalue(2,1,2)=0.0,
>>> starting_ns_eigenvalue(3,1,2)=1.0,
>>> starting_ns_eigenvalue(4,1,2)=1.0,
>>> starting_ns_eigenvalue(5,1,2)=1.0,
>>>
>>>
>>> The output file is:
>>> LDA+U parameters:
>>> U(  2) =   8.0000   J(  2) =   1.0600   B(  2) =   0.1217
>>> atom    9   Tr[ns(na)] (up, down, total) =   4.00000  0.19494  4.19494
>>>    spin  1
>>>     eigenvalues:
>>>   0.000  1.000  1.000  1.000  1.000
>>>     eigenvectors:
>>>   0.110  0.701  0.037  0.000  0.153
>>>   0.795  0.016  0.023  0.000  0.166
>>>   0.000  0.004  0.885  0.000  0.111
>>>   0.096  0.279  0.055  0.000  0.570
>>>   0.000  0.000  0.000  1.000  0.000
>>>     occupations:
>>>   0.890 -0.295  0.000 -0.102  0.000
>>>  -0.295  0.205  0.000 -0.276  0.000
>>>   0.000  0.000  1.000  0.000  0.000
>>>  -0.102 -0.276  0.000  0.904  0.000
>>>   0.000  0.000  0.000  0.000  1.000
>>>    spin  2
>>>     eigenvalues:
>>>   0.020  0.020  0.021  0.065  0.070
>>>     eigenvectors:
>>>   0.000  0.512  0.416  0.071  0.000
>>>   0.000  0.004  0.193  0.803  0.000
>>>   0.542  0.000  0.000  0.000  0.458
>>>   0.000  0.484  0.390  0.126  0.000
>>>   0.458  0.000  0.000  0.000  0.542
>>>     occupations:
>>>   0.023  0.010  0.000  0.005  0.000
>>>   0.010  0.056  0.000  0.014  0.000
>>>   0.000  0.000  0.043  0.000 -0.025
>>>   0.005  0.014  0.000  0.026  0.000
>>>   0.000  0.000 -0.025  0.000  0.047
>>> atomic mag. moment =     3.805060
>>>
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>>
>>
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