[QE-users] Berry phase calculation of negatively charged NV center

[Anil Bilgin]

I have not carried out this calculation without spin polarization. However,
spin polarization should be supported according to the source file header.
Also, I believe not doing a spin-polarized calculation would yield an
unphysical result, as the NV- center in diamond has a net spin. I suspect
the simulation would not converge and bounce around the many
close-to-degenerate answers in the case of spin unpolarized calculations?

Thank you,
Anil Bilgin


On Thu, Dec 19, 2019 at 7:12 AM Paolo Giannozzi <p.giannozzi at gmail.com>
wrote:

> I can confirm that the latest version of the code yields the same results.
> No idea why. Do you get a similar behavior without spin polarization?
>
> Paolo
>
> On Tue, Dec 17, 2019 at 8:05 AM Anil Bilgin <bilgin at uchicago.edu> wrote:
>
>> Hello all,
>>
>> I am trying to calculate the permanent electric dipole moment of a
>> negatively charged NV center in diamond. All NV centers are oriented along
>> the 111 direction of diamond, which means that (by symmetry) contributions
>> to polarizations along all three reciprocal lattice vectors should be equal
>> in magnitude. While this is the case for my reciprocal lattice vectors
>> along gdir = 2, 3; gdir = 1 gives me a vastly different answer. If anyone
>> knows why this calculation is going wrong, or if this kind of calculation
>> can / cannot be done in this way, please let me know. Other relevant
>> information is below.
>>
>> Thank you,
>> Anil Bilgin
>>
>> PhD candidate
>> Pritzker School of Molecular Engineering
>> University of Chicago
>>
>>
>> I'm using QE version 6.1+intelmpi-5.1+intel-16.0
>>
>> Little information about inputs: 'scf' calculations are done on an
>> already relaxed structure with 215 atoms. Since the supercell is
>> sufficiently large, k-point mesh is taken to be 1x1x1 (basically the gamma
>> point).
>>
>>
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>
>
> --
> Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
> Phone +39-0432-558216, fax +39-0432-558222
>
> _______________________________________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)
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