[QE-users] How can we decide the spin state of the relaxed structure
Andrii Shyichuk
andrii.shyichuk at chem.uni.wroc.pl
Tue Oct 27 14:14:55 CET 2020
Dear Naga,
>From your magnetization data I can see that there is a significant
spin-down on Co and some significant spin-ups on the other sites.
This fact on itself indicates two or more magnetization sites, no matter
what the total magnetization says. If you wanted it to be on Co only -
well, it is not only there - as there are other sites.
Please note that these values correspond to non-overlapping atomic
spheres, meaning that actual Co magnetization is (much) higher than the
displayed values.
As to why in particular does it happen the way it happen - I do not have
a precise answer.
You may try pseudopotentials with spin-orbit coupling, or an
all-electron code, or a molecular code (atomic-orbital based,
non-periodic, e.g. Gaussian) just to see if you get the same result.
Best regards.
Andrii
W dniu 2020-10-27 09:38, samala nagaprasad reddy napisał:
> 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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