[QE-users] How can we decide the spin state of the relaxed structure

samala nagaprasad reddy snpreddy63 at gmail.com
Tue Oct 27 09:38:29 CET 2020


Dear Andrii Shyichuk,

Thank you so much, for your detailed explanation.

1. The starting magnetization result is weird.
> There are apparently a few areas/centers of magnetization, summing up to
> 2.77 absolute magnetization.
> Some of them are up, and some of them are down, hence the total
> magnetization (spin up minus spin down) is 0.3.
>
> Plot the magnetization to see what happens, while atomic magnetizations
> can be found in the output file, after the SCF steps.
> Same goes for the other results. Without the magnetization plot, you
> cannot know if it is localized where it should be.
>
>
>From the starting_magnetization output, the Magnetic moment data is copied
here. Atom 24 is Co.
Magnetic moment per site:
atom:    1    charge:    0.8381    magn:   -0.0072    constr:    0.0000
atom:    2    charge:    0.7359    magn:   -0.0151    constr:    0.0000
atom:    3    charge:    0.7788    magn:    0.0076    constr:    0.0000
atom:    4    charge:    0.8093    magn:   -0.0269    constr:    0.0000
atom:    5    charge:    0.8320    magn:    0.0067    constr:    0.0000
atom:    6    charge:    0.8322    magn:   -0.0195    constr:    0.0000
atom:    7    charge:    0.7581    magn:   -0.0037    constr:    0.0000
atom:    8    charge:    0.7590    magn:    0.0002    constr:    0.0000
atom:    9    charge:    0.8329    magn:   -0.0237    constr:    0.0000
atom:   10    charge:    0.8393    magn:    0.0090    constr:    0.0000
atom:   11    charge:    0.8295    magn:   -0.0245    constr:    0.0000
atom:   12    charge:    0.7706    magn:    0.0020    constr:    0.0000
atom:   13    charge:    0.7626    magn:   -0.0058    constr:    0.0000
atom:   14    charge:    0.8298    magn:   -0.0171    constr:    0.0000
atom:   15    charge:    0.8408    magn:    0.0053    constr:    0.0000
atom:   16    charge:    0.8308    magn:   -0.0263    constr:    0.0000
atom:   17    charge:    0.8158    magn:    0.0082    constr:    0.0000
atom:   18    charge:    0.8036    magn:   -0.0166    constr:    0.0000
atom:   19    charge:    0.8416    magn:   -0.0047    constr:    0.0000
atom:   20    charge:    0.7640    magn:    0.0021    constr:    0.0000
atom:   21    charge:    1.1987    magn:    0.0034    constr:    0.0000
atom:   22    charge:    1.1930    magn:    0.0031    constr:    0.0000
atom:   23    charge:    1.1107    magn:    0.0027    constr:    0.0000
atom:   24    charge:   13.1659    magn:   -0.2418    constr:    0.0000
atom:   25    charge:    0.2760    magn:    0.0001    constr:    0.0000
atom:   26    charge:    0.3021    magn:    0.0001    constr:    0.0000
atom:   27    charge:    0.3101    magn:    0.0002    constr:    0.0000
atom:   28    charge:    0.3305    magn:   -0.0002    constr:    0.0000
atom:   29    charge:    0.3365    magn:    0.0006    constr:    0.0000
atom:   30    charge:    0.1946    magn:   -0.0002    constr:    0.0000
atom:   31    charge:    0.2463    magn:    0.0000    constr:    0.0000
atom:   32    charge:    0.2932    magn:    0.0001    constr:    0.0000
atom:   33    charge:    1.7268    magn:    0.1731    constr:    0.0000
atom:   34    charge:    0.7468    magn:    0.0702    constr:    0.0000
atom:   35    charge:    0.7615    magn:   -0.0003    constr:    0.0000
atom:   36    charge:    0.7542    magn:   -0.0003    constr:    0.0000
atom:   37    charge:    0.7593    magn:   -0.0002    constr:    0.0000
atom:   38    charge:    4.5377    magn:   -0.0011    constr:    0.0000
atom:   39    charge:    4.5690    magn:   -0.0003    constr:    0.0000
atom:   40    charge:    4.6764    magn:    0.0001    constr:    0.0000
atom:   41    charge:    4.5738    magn:   -0.0016    constr:    0.0000
atom:   42    charge:    4.6399    magn:   -0.0014    constr:    0.0000
atom:   43    charge:    4.5299    magn:    0.0010    constr:    0.0000
atom:   44    charge:    4.5786    magn:   -0.0005    constr:    0.0000
atom:   45    charge:    4.6315    magn:    0.0004    constr:    0.0000
atom:   46    charge:    4.5206    magn:   -0.0010    constr:    0.0000
atom:   47    charge:    0.5296    magn:   -0.0002    constr:    0.0000
atom:   48    charge:    0.4843    magn:    0.0001    constr:    0.0000
atom:   49    charge:    0.4805    magn:    0.0001    constr:    0.0000
atom:   50    charge:    0.7915    magn:    0.0004    constr:    0.0000

also for triplet
Magnetic moment per site:
atom:    1    charge:    0.8449    magn:    0.0240    constr:    0.0000
atom:    2    charge:    0.8523    magn:    0.0012    constr:    0.0000
atom:    3    charge:    0.8486    magn:    0.0115    constr:    0.0000
atom:    4    charge:    0.8396    magn:    0.0167    constr:    0.0000
atom:    5    charge:    0.8456    magn:    0.0011    constr:    0.0000
atom:    6    charge:    0.8365    magn:    0.0249    constr:    0.0000
atom:    7    charge:    0.8556    magn:   -0.0025    constr:    0.0000
atom:    8    charge:    0.8510    magn:    0.0182    constr:    0.0000
atom:    9    charge:    0.8398    magn:    0.0083    constr:    0.0000
atom:   10    charge:    0.8441    magn:    0.0092    constr:    0.0000
atom:   11    charge:    0.8393    magn:    0.0207    constr:    0.0000
atom:   12    charge:    0.8550    magn:   -0.0019    constr:    0.0000
atom:   13    charge:    0.8515    magn:    0.0209    constr:    0.0000
atom:   14    charge:    0.8406    magn:    0.0016    constr:    0.0000
atom:   15    charge:    0.8425    magn:    0.0181    constr:    0.0000
atom:   16    charge:    0.8402    magn:    0.0121    constr:    0.0000
atom:   17    charge:    0.8502    magn:    0.0036    constr:    0.0000
atom:   18    charge:    0.8494    magn:    0.0218    constr:    0.0000
atom:   19    charge:    0.8491    magn:   -0.0025    constr:    0.0000
atom:   20    charge:    1.3952    magn:    0.0006    constr:    0.0000
atom:   21    charge:    1.3895    magn:    0.0006    constr:    0.0000
atom:   22    charge:    1.3892    magn:    0.0015    constr:    0.0000
atom:   23    charge:    1.3950    magn:    0.0021    constr:    0.0000
atom:   24    charge:   14.3334    magn:   -0.2847    constr:    0.0000
atom:   25    charge:    0.4321    magn:    0.0003    constr:    0.0000
atom:   26    charge:    0.4222    magn:   -0.0010    constr:    0.0000
atom:   27    charge:    0.4239    magn:    0.0000    constr:    0.0000
atom:   28    charge:    0.4226    magn:   -0.0011    constr:    0.0000
atom:   29    charge:    0.4212    magn:   -0.0003    constr:    0.0000
atom:   30    charge:    0.4213    magn:   -0.0011    constr:    0.0000
atom:   31    charge:    0.4205    magn:   -0.0002    constr:    0.0000
atom:   32    charge:    0.4206    magn:   -0.0007    constr:    0.0000
atom:   33    charge:    0.4231    magn:    0.0000    constr:    0.0000
atom:   34    charge:    0.4319    magn:    0.0002    constr:    0.0000
atom:   35    charge:    0.4321    magn:    0.0004    constr:    0.0000
atom:   36    charge:    0.4317    magn:    0.0004    constr:    0.0000
atom:   37    charge:    0.7670    magn:   -0.0001    constr:    0.0000
atom:   38    charge:    0.7665    magn:   -0.0004    constr:    0.0000
atom:   39    charge:    0.7674    magn:   -0.0008    constr:    0.0000
atom:   40    charge:    4.6219    magn:    0.0002    constr:    0.0000
atom:   41    charge:    4.6196    magn:    0.0034    constr:    0.0000
atom:   42    charge:    4.6190    magn:    0.0010    constr:    0.0000
atom:   43    charge:    4.6186    magn:    0.0036    constr:    0.0000
atom:   44    charge:    4.6223    magn:    0.0006    constr:    0.0000
atom:   45    charge:    4.6175    magn:    0.0028    constr:    0.0000
atom:   46    charge:    4.6205    magn:    0.0013    constr:    0.0000
atom:   47    charge:    4.6207    magn:    0.0041    constr:    0.0000
atom:   48    charge:    4.6210    magn:    0.0015    constr:    0.0000
atom:   49    charge:    3.0620    magn:    0.3267    constr:    0.0000
atom:   50    charge:    3.0232    magn:    0.4564    constr:    0.0000

> I assume that there is only one Co atom in the system, and the
> magnetization should be localized there.
> In the starting magnetization result, it is not.
>
Why is it not localized in the starting_magnetization results?

>
> 2. The triplet state has a lower energy, so yes, it looks more stable. Is
> it also more stable in the experimental data?
>
No experimental data available.

>
> 3. I'd say, the better approach is the one giving you a reasonable result.
> The tot_magnetization calculations are stable in a sense that they are
> likely to converge with the desired magnetization.
> The starting_magnetization are less stable from my experience: low-spin
> states can converge from high-spin starting_magnetization.
>
I also felt the same from my experience, thanks for the confirmation.

Thank you
Naga

>
> Best regards.
> Andrii Shyichuk
>
> W dniu 2020-10-21 09:52, samala nagaprasad reddy napisał:
>
> Hello QE experts,
>
> I am trying spin polarized DFT studies of Co-corrole complex using QE
> (using just gamma point and large box size to avoid interactions),  I am
> relaxing the structure using  nspin = 2 and  starting_magnetization(6) =
> 1.0, as initial guess of Co atom. At the end of relaxation I have observed
> the below
>
> total magnetization       =     0.31 Bohr mag/cell
> absolute magnetization    =     2.77 Bohr mag/cell
> and Final energy   =   -1144.9536036757 Ry
>
> When I minimize the structure in singlet and triplet states by fixing the
> total magnetization (non spin polarized gives singlet state, and used
> tot_magnetization = 2 for triplet). The relaxed energies are
>     Final energy   =   -1144.9318071744 Ry  (singlet)
>     Final energy   =   -1144.9537812641 Ry  (triplet)
>
> Regarding this I have few queries
> 1) what is the spin state of the relaxed complex with
> starting_magnetization(6) = 1.0 (singlet/triplet or any other)? It seems
> the electronic spin state is singlet bec the total magnetization is 0.31
> and is close to 0.
> 2) In the spin restricted calculations, the triplet state is more stable
> than the singlet and how can we understand it from the above?
> 3) which approach is better (whether the guess starting_magnetization or
> by fixing the total magnetization)?
>
> Thanks in advance
> Naga
>
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>
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