Convergence Behavior of Spin Moments in Noncollinear Magnetic Order. ~ energycutoff and Kgrid ~ |
- Date: 2025/06/02 16:52
- Name: Soichiro Kikuchi
<akatuki3329@gmail.com>
- Dear developers,
My report and question are about Convergence Behavior of Spin Magnetic Moments in Noncollinear Magnetic Order.
I am trying to calculation the spin magnetic moment in noncollinear magnetic order, such as Mn₃Sn and Mn₃CuN."
To investigate the convergence behavior of spin magnetic moments of Mn3Sn, I performed calculations using various values of energy cutoff and Kgrid.
First, I fixed the k-point grid at 12×12×12 and examined the convergence with respect to the energy cutoff. The magnitude of the local spin magnetic moment on the magnetic atom Mn converged at an energy cutoff of around 400–500 Ryd.
However, the total spin magnetic moment, in terms of both its magnitude and orientation, did not show clear convergence until the cutoff was increased to approximately 7000 Ryd, which is significantly higher than the typical values recommended in the manual.
Next, keeping the energy cutoff fixed at 7000 Ryd, I varied the Kgrid to assess its influence. However, the results did not show a clear or systematic convergence behavior, and it became difficult to determine an appropriate Kgrid for reliable calculations.
Below is an excerpt from the summary of the convergence results.
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Kgrid = 12×12×12
①cutoff = 200
local spin moment = 3.38,
Total spin moment = 0.1424, theta = 89.99, phi = 118.015
②cutoff = 400
local spin moment = 3,38,
Total spin moment = 0.0430, theta = 89.88, phi = 118.95
③cutoff = 600
local spin moment = 3,38,
Total spin moment = 0.0135, theta = 89.99, phi = 115.48
④cutoff = 800
local spin moment = 3,38,
Total spin moment = 0.0101, theta = 90.10, phi = 113.55
⑤cutoff = 1000
local spin moment = 3,38,
Total spin moment = 0.0072, theta = 90.16, phi = 141.72
⑥cutoff = 2000
local spin moment = 3,38,
Total spin moment = 0.0048, theta = 90.10, phi = 152.68
⑦cutoff = 3000
local spin moment = 3,38,
Total spin moment = 0.0042, theta = 89.95, phi = 158.50
⑧cutoff = 3500
local spin moment = 3,38,
Total spin moment = 0.0030, theta = 89.89, phi = 98.42
⑨cutoff = 4000
local spin moment = 3,38,
Total spin moment = 0.0028, theta = 89.94, phi = 96.16
⑩cutoff = 5000
local spin moment = 3,38,
Total spin moment = 0.0026, theta = 90.17, phi = 94.29
⑪cutoff = 6000
local spin moment = 3,38,
Total spin moment = 0.0025, theta = 89.99, phi = 93.04
⑫cutoff = 7000
local spin moment = 3,38,
Total spin moment = 0.0024, theta = 89.99, phi = 91.95
⑬cutoff = 8000
local spin moment = 3,38,
Total spin moment = 0.0025, theta = 90.00, phi = 93.72
⑭cutoff = 9000
local spin moment = 3,38,
Total spin moment = 0.0024, theta = 89.98, phi = 91.60
energycutoff = 7000
①Kgrid = 15 15 12
local spin moment = 3,38,
Total spin moment = 0.0065, theta = 90.19, phi = 123.92
②Kgrid = 18 18 12
local spin moment = 3,38,
Total spin moment = 0.014, theta = 89.98, phi = 108.90
③Kgrid = 24 24 12
local spin moment = 3,38,
Total spin moment = 0.0033, theta = 90.20, phi = 119.95
④Kgrid = 27 27 12
local spin moment = 3,38,
Total spin moment = 0.0026, theta = 90.44, phi = 164.10
⑤Kgrid = 30 30 12
local spin moment = 3,38,
Total spin moment = 0.00099, theta = 89.91, phi = -67.39
energycutoff = 8000
Kgrid = 25 25 12
local spin moment = 3.38
Total spin moment = 0.001584, theta = 90.14, phi = 14.9
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For comparison, the calculation results obtained using VASP are presented. These results are in good agreement with the experimentally observed values.
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local spin moment = 2.90,
Total spin moment = 0.003, theta = 90.00, phi = 0
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Last, input file used is noted.
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Species.Number 2
<Definition.of.Atomic.Species
Mn Mn6.0-s3p2d1 Mn_PBE19
Sn Sn7.0-s3p2d2 Sn_PBE19
Definition.of.Atomic.Species>
Atoms.Number 8
Atoms.SpeciesAndCoordinates.Unit FRAC
<Atoms.SpeciesAndCoordinates
1 Mn 0.8418997760617231 0.6837995580507723 0.2499994261181939 9.0 6.0 90.0 0.0 90.0 0.0 0 off
2 Mn 0.1580997540495446 0.3161995080990891 0.7500005346670946 9.0 6.0 90.0 0.0 90.0 0.0 0 off
3 Mn 0.3162006822288461 0.1581007910616492 0.2499994261181939 9.0 6.0 90.0 -120.0 90.0 -120.0 0 off
4 Mn 0.6837998848945261 0.8419003491124215 0.7500005346670946 9.0 6.0 90.0 -120.0 90.0 -120.0 0 off
5 Mn 0.8419001029054840 0.1581007910616492 0.2499994261181939 9.0 6.0 90.0 120.0 90.0 120.0 0 off
6 Mn 0.1581004642178954 0.8419003491124215 0.7500005346670946 9.0 6.0 90.0 120.0 90.0 120.0 0 off
7 Sn 0.3333330220499562 0.6666660440999053 0.2499994261181939 7.0 7.0 90.0 0.0 90.0 0.0 0 off
8 Sn 0.6666665080613186 0.3333330220499562 0.7500005346670946 7.0 7.0 90.0 0.0 90.0 0.0 0 off
Atoms.SpeciesAndCoordinates>
Atoms.UnitVectors.Unit Ang
<Atoms.UnitVectors
5.5674400329999996 0.0000000000000000 0.0000000000000000
-2.7837200164999998 4.8215445026000001 0.0000000000000000
0.0000000000000000 0.0000000000000000 4.4320101738000002
Atoms.UnitVectors>
scf.Constraint.NC.Spin off
scf.XcType GGA-PBE
scf.SpinPolarization nc
scf.partialCoreCorrection on
scf.SpinOrbit.Coupling on
scf.ElectronicTemperature 0.0
scf.energycutoff 600
scf.maxIter 1000
scf.EigenvalueSolver band
scf.Kgrid 12 12 12
scf.Mixing.Type rmm-diisk
scf.Init.Mixing.Weight 0.05
scf.Min.Mixing.Weight 0.01
scf.Max.Mixing.Weight 0.30
scf.Mixing.History 25
scf.Mixing.StartPulay 15
scf.criterion 1.0e-8
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I would like to know that what is the cause of these problems.
Thank you very much.
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