[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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