Questions tagged [magnetism]
For questions about magnetic systems and materials
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questions
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Modeling magnetic field of permanent magnet - where to start?
I would like to model magnetic field of a permanent magnet like this one magnet . Ideally, I would like to do it python or any other language. I would like to start with some simple geometry and some ...
5
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34 views
What are Crystal Electric Field Parameters?
What does the following notation mean?
$$A_{20}\left<r^2\right> = -100 \mathrm{K}$$
Where $A_{20}$ is termed a Crystal Electric Field Parameter.
I often see this notation when reading papers on ...
5
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0answers
20 views
How to change the magnetization direction in Quantum ESPRESSO?
I have a magnetic crystal system. I want to calculate the total energy of the system if the magnetization direction is aligned in different directions such as [110], [010]. By default Quantum ESPRESSO ...
8
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1answer
50 views
How is SYMPREC used to determine symmetries compatible with local magnetic moments in VASP?
In DFT calculations using vasp, symmetry analysis are performed to determine space group symmetries at first, if symmetrization is turned on, such as ISYM = 2. When magmoms are set in INCAR, ...
5
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1answer
62 views
How to make ferro, feri and antiferro magnetic structure for QE
I have below &SYSTME information from my input file
...
8
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2answers
168 views
Magnetic Transition Pymatgen Error
I am trying to simulate the change in magnetic moments during a ferromagnetic to antiferromagnetic transition.
...
10
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1answer
84 views
Why does the S squared value have no meaning in Density Functional Theory?
It is not the first time that I stumble upon the affirmation that spin and the $S^2$ value, under DFT, has no "real physical meaning". Why?
If that is true, why are we using it all the time ...
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72 views
Band unfolding for magnetic systems [closed]
I'm trying to study the electronic structure of a 1D antiferromagnetic (in which the spin is associated with copper atoms) system, via spin-polarized calculations.
The unit cell dimensions are ...
10
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1answer
114 views
How can I calculate the J value in an antiferromagnetic material?
I am new to DFT, especially in doing DFT for magnetic materials. I recently came across this paper which indicated the calculation of the J value in the case of antiferromagentic materials as per the ...
7
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1answer
124 views
How to study a new material without any experimental data about it?
My question is a little bit general. I want to study a 2D monolayer material which hasn't any experimental data available, just some first principles DFT works using PBE, LDA and HSE06 (for band ...
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52 views
Handling multiple self-consistent solutions with DFT+U
It is well-established that within the DFT+U framework, one can achieve several self-consistent solutions with greatly varying energies for the same exact magnetic ordering. In 2010, Meredig et al. ...
4
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1answer
103 views
How can I obtain seperate spin-up and spin-down bands while considering Spin Orbit Coupling in Quantum ESPRESSO?
I have been studying a magnetic material with SoC taken into consideration. The main aim was to obtain the band structure.
when I use spin_component = 1 in the ...
5
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1answer
38 views
Are these settings for HSEsol accurate enough?
I have conducted HSEsol relaxation on a monolayer unit cell of 3 atoms using VASP, with the settings below :
...
7
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1answer
86 views
Will there be a difference between GGA and GGA+$U$ for material with Sc element involved?
I have a material that contains the transition metal element Sc [3$d$1], and I want to know your opinions if there will be a difference between GGA and GGA+$U$ calculation. Knowing that the other ...
9
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1answer
182 views
How to perform HSEsol in VASP calculations?
I want to perform HSEsol (PBEsol + HSE06) calculation on a material (monolayer) that doesn't have experimental data available. Could you please tell me how to ...
6
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0answers
26 views
Is it possible to calculate the variation of magnetization M(T) for a diluted magnetic semiconductor?
Is there any simulation program (for example a DFT package) to determine the variation of magnetization M(T) for dilute magnetic semiconductors or doped semiconductors with different concentrations of ...
9
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2answers
208 views
Can we consider SOC in FM materials using QE?
This is a follow-up question to my question posted here. I've been trying to study the effects of spin-orbit coupling (SOC) on the band structure of ferromagnetic (FM) material VSe$_{2}$. The input ...
7
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3answers
541 views
How to determine the value of the difference (U-J) in "Dudarev's approach" for GGA+U calculation using the VASP?
I want to conduct GGA+U calculations using Duradev's approach in VASP code on a ...
6
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1answer
122 views
How can I properly represent paramagnetic materials in DFT calculations?
I have seen specific ways of constructing input files for
Anti-ferromagnetic materials
Ferromagnetic materials.
How can I represent a paramagnetic material in plane wave DFT codes like Quantum ...
11
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1answer
290 views
Are different eigensolvers consistent within VASP (Algo=Normal vs Fast)
I tried to relax a 4x4x1 supercell of ferromagnetic monolayer material using the default settings (ALGO = Normal) but it didn't converge. So, I switched to ...
9
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1answer
182 views
PT-symmetry leading to spin-degenerate band structures
I am trying to understand the fundamental physics of a kind of problem. I will introduce a specific example and then list some of the broader qualms I hold. I have observed many band structures, be it ...
12
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2answers
442 views
Getting different total magnetic moment in 'scf' and 'vc-relax' calculations in Quantum ESPRESSO
I am performing a spin polarized DFT calculations in Quantum Espresso on a Co2MnSi ferromagnetic crystal. For this I have performed these steps:
1) Performed ...
18
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3answers
746 views
Ising model: How can I spot the critical point?
Consider a zero-field Ising model with $N$ spins and periodic boundary conditions, with the Hamiltonian given by:
$$H = -K \sum _{(ij)} s_i s_j\tag{1}$$
in 1D and 2D, where $K = \frac{J}{k_BT}$, where ...
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4answers
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Is it possible to calculate the Curie temperature for magnetic systems?
Using DFT calculations we can know the electronic and magnetic property of the system at 0 K. I am wondering if there is any computational method to know the curie temperature of magnetic materials? ...
9
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1answer
235 views
Is the "Final Magnetic moment" in the materials project repository same as the "total magnetization" value in Quantum ESPRESSO output files?
I'm quite new to spin-polarized DFT and have been trying to study $BaVSe_{3}$ which is ferromagnetic (with a Final Magnetic Moment of 0.052 Bohr Mag) as per the Materials Project repository [picture 1]...
6
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1answer
41 views
How can I assign spins to an non-planar Anti-Ferro Magnetic system (CoO in this case)?
I have been working with an anti-ferromagnetic material Cobalt Oxide. And in the image given below the blue spheres are Co ions. The blue spheres form a tetrahedron shape.
And I've assigned the spin ...
13
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3answers
201 views
Are there any codes to study magnetic materials?
I have used a few codes for studying magnetic materials (specifically core-shell nanoparticles with an AFM shell and an FM core). These are:
Vampire: For the calculation of curie temperature via ...
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0answers
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Orbital magnetization in periodic solids
The orbital magnetization in periodic solids has been nicely described by the so-called modern theory of magnetization [1,2,3,4].
$$\tag{1}
\mathcal{M}_{orb} = -\frac{1}{2} \Im \sum_{n,\mathbf{k}} f_{...
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1answer
134 views
How to calculate the exchange matrix of a bilayer magentic system?
I have been using the Vampire atomistic simulation software for a while and it has a useful simulation for predicting the curie temperature. But in order to do that I need the exchange matrix of Co-...
9
votes
2answers
141 views
How to visualize MuMax3 shapes?
I'm new to micromagnetics and the finite difference method. The mumax3 software lets you create a variety of geometric shapes. I would like to create a core-shell particle to study magneto-electric ...
8
votes
1answer
67 views
How to predict new Half Metallic materials with higher degree of spin polarization?
Using DFT calculations, how one can predict the new half metallic materials with higher degree of spin polarization. I want to know the steps which have to be followed in prediction of new materials. ...
9
votes
1answer
716 views
How to do spin polarization calculations using Quantum ESPRESSO?
I am currently new to DFT calculations in Quantum ESPRESSO. Though, I have read some research papers for determining spin polarization and Half-metallicity in certain Heusler alloys. These research ...
11
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1answer
137 views
Predicting magnetic moment of a metal complex computationally
Recently, for entrance exams, I have been dealing with a lot of weird compounds. One of them is $\ce{K3[Mn(CN)6]}$.
The objective was to predict the magnetic moment of the above complex.
I predict ...
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2answers
1k views
When should spin polarized calculations be done?
Should the presence of a d block element in the unit cell mandate the need for performing spin-polarized calculations? I wanted to find out the DOS, PDOS, and the band structure. I'm new to DFT and I'...
10
votes
1answer
241 views
How to automatically plot atomic structures with magnetic moments?
I work with magnetic materials and I haven't found a way to automatically plot structures with their corresponding magnetic moments. For this specific project I am using VASP. I am trying to plot ...
11
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1answer
100 views
Spin density in systems with non-collinear magnetism using VASP
I have recently been working with non-collinear antiferromagnetic systems. I understand that, in order to obtain spin density, one must obtain the electron density in one configuration of spin and ...
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3answers
1k views
Magnetism and Topology
Can magnetism and topological insulating behavior coexist in a material? If yes, can someone refer to a recent work?
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1answer
100 views
What measured quantity can be associated to the value of the J parameter in the Heisenberg/Ising hamiltonians?
This question is related to other one here in the MatterModelingSE:
Is it possible to calculate/estimate the value of the J parameter to be used in the Heisenberg/Ising hamiltonians?
Here J is the ...
6
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1answer
136 views
Is it possible to calculate/estimate the value of the J parameter to be used in the Heisenberg/Ising Hamiltonians?
Studying magnetic systems, two frequently used approximations are the Heisenberg and Ising models (a discussion about these approximations can be read here):
\begin{equation}
\tag{Heisenberg}
\hat{H}...
14
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1answer
93 views
How accurately are magnetic effects treated in *ab initio* methods?
I am a condensed matter theorist and I mostly use quantum Monte Carlo methods. I use models like the Heisenberg model, an represent an extreme simplification of real materials to just localized spin ...
6
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1answer
222 views
How is the material $\ce{\alpha-NaMnO2}$ pronounced?
I am a theoretical physicist, so I am not very familiar with chemical names. The material I am interested in is $\ce{\alpha-NaMnO2}$. Would that be pronounced alpha sodium manganese dioxide? Is it ...
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1answer
332 views
Is Heisenberg model or in its simplier form Ising model a good approximation to study magnetic systems?
Heisenberg model
$$\hat{H}=-\sum_{\langle i j\rangle}J\hat{S}_i\hat{S}_j$$
And in its simplified version, the Ising model
$$\hat{H}=-\sum_{\langle ij\rangle}J\hat{S}_i^z\hat{S}_j^z$$
are widely ...
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3answers
252 views
What are examples of materials that closely correspond to the Heisenberg model?
I use the antiferromagnetic Heisenberg model all the time:
$ H = J \sum \limits_{\langle i,j \rangle} \vec S_i \cdot \vec S_j$
What are some examples of materials that are well-described by this ...
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2answers
55 views
How does magnetic anisotropy cause stable long range magnetic ordering in quasi-one-dimensional solids?
According to Mermin-Wagner theorem ferro/antiferromagnetic ordering cannot occur in ideal one dimensional systems. However there exists quasi-one-dimensional ferromagnetic materials attributing its ...
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1answer
44 views
Does the thermal evolution of molecular structures critically affect the validity of the calculated magnetic anisotropy?
This is a particular aspect I'm interested in, from the more generic question
"Does the thermal evolution of chemical structures critically affect the validity of the calculated physical properties?". ...
16
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2answers
224 views
Is there any good review paper on the density matrix renormalization group (DMRG) method?
I would appreciate if someone could recommend me good review literature on the density matrix renormalization group (DMRG) method, especially for magnetic systems.
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1answer
217 views
Calculation of the relative energies in a Spin Crossover material
Spin Crossover (SCO) complexes are a particular type of molecular entities which are usually formed by a metal ion (general $\ce{Fe(II)}$ or $\ce{Co(III)}$) complexed by several ligands with donor N ...
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1answer
99 views
How to model phase transitions at critical regions in a magnetic system?
Is there any first principle method available to study phase transitions at the critical region for ferromagnetism (FM) or antiferromagnetism (AFM)?
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1answer
85 views
Best partial atomic charges estimate for crystal field purposes?
The estimates for partial atomic charges start with the very simple Mulliken analysis, which we all study in class, but which is known to be very limited. Beyond this, there is a range of ...
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1answer
141 views
How to evaluate spin exchange parameters of a magnetic material using DFT?
I think we have to calculate total energies using different FM, AFM configurations and solve a set of linear equations. How to arrive at the set of equations for any given structure?
An example from ...