24 votes
Accepted

Is there any good review paper on the density matrix renormalization group (DMRG) method?

2003: Book chapter by Karen Hallberg. 2004: Reviews of Modern Physics by Ulrich Schollwoeck (2818 current citations). 2006: Advances in Physics by Karen Hallberg. 2008: JCTN: by Gabriele De Chiara ...
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17 votes
Accepted

Ising model: How can I spot the critical point?

My question is, when I run a simulation with $N$ particles and I track the Hamiltonian per particle $(H/N)$ and the magnetization per particle $\left(\sum _i s_i /N\right)$, with $K$ values going from ...
  • 4,403
15 votes
Accepted

Best partial atomic charges estimate for crystal field purposes?

There are a few recent atomic partial charge schemes that are useful. You mentioned the electrostatic fitting schemes. These seek to best match the electrostatic potential of the molecule / system, ...
15 votes
Accepted

Is it possible to calculate the Curie temperature for magnetic systems?

This is an important question, and I will do my best to answer it in a way that adds to the nice suggestions made in earlier answers. In short, the answer is yes, but only with the help of some other ...
  • 166
14 votes

Ising model: How can I spot the critical point?

As Anyon correctly pointed out, there is no phase transition at finite temperature in 1D. In 2D there are a number of different ways to identify the phase transition (I'm assuming you're using Monte ...
13 votes

How to evaluate spin exchange parameters of a magnetic material using DFT?

First of all, you need to be familiar with models for magnetic exchange. Two important examples are Heisenberg and Ising: Depending on the system you are studying, you will be using one of these. ...
  • 1,421
13 votes

Is it possible to calculate the Curie temperature for magnetic systems?

I am wondering if there is any computational method to know the curie temperature of magnetic materials? Yes, there is!. Simulations to determine Curie Temperature are usually done via Monte-Carlo ...
  • 4,278
12 votes
Accepted

Is Heisenberg model or in its simplier form Ising model a good approximation to study magnetic systems?

Introduction Your question reminds me of a quote by Paul Dirac, The underlying physical laws necessary for the mathematical theory of a large part of physics and the whole of chemistry are thus ...
  • 4,403
12 votes
Accepted

Are different eigensolvers consistent within VASP (Algo=Normal vs Fast)

Changing ALGO should make no difference in an ideal world. However, when you invoke spin polarization, you may find a different magnetic state from both algorithms. The best practice would be to ...
11 votes

Magnetism and Topology

Not a very thorough answer, but it should get the ball rolling. Spontaneous magnetization or extrinsically magnetic TIs have been achieved through defect engineering in non-magnetic Topological ...
10 votes
Accepted

How is the material $\ce{\alpha-NaMnO2}$ pronounced?

The anions of the form $\ce{MnO_x^y-}$ are referred to as manganates (see Wikipedia). I'm not sure if there might be a "special" name for $\ce{MnO2^-}$ specifically (that's the species you have here) ...
10 votes
Accepted

Calculation of the relative energies in a Spin Crossover material

The question highlights the difficulty in calculating an ab initio value for $T_{1/2}$ for a molecule like $\textrm{Fe(Phen)}_2\textrm{(SCN)}_2$, and specifically the fact that a highly cited 2018 ...
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10 votes

Magnetism and Topology

Magnetic order and topological order can exist simultaneously. In fact, what one may call the very first proposal of an instrinsic topological material was Haldane's model from 1988, which is an ...
  • 10.6k
10 votes

When should spin polarized calculations be done?

Unfortunately, without performing spin polarized calculations you cannot know if it will matter. Further, you must perform different magnetic configurations (AFM, FM, PM) to know which is stable. ...
10 votes

Is it possible to calculate the Curie temperature for magnetic systems?

(I'll answer with crystalline solids in mind.) You could study the material's magnetic and non-magnetic phases and construct their Gibbs free energy (G) vs temperature (T) profiles. \begin{equation} G\...
10 votes
Accepted

How to study a new material without any experimental data about it?

Structural: You should investigate the stability of your structure. In detail, you should verify: Dynamical stability: phonon spectrum. Thermal stability: molecular dynamics (MD) simulations ...
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9 votes

How to automatically plot atomic structures with magnetic moments?

This took some digging, but I can supply at least a partial answer. Assuming you can copy the list of magnetic moments to a list, you could trick whatever software you are using for visualization into ...
9 votes
Accepted

When should spin polarized calculations be done?

I agree with Tristan that the fool proof method is to do a spin-polarized self consistent calculation and look at the final magnetic moment. If the final magnetic moment is non-zero you should include ...
  • 8,452
9 votes

How does magnetic anisotropy cause stable long range magnetic ordering in quasi-one-dimensional solids?

At least in the example you picked up to illustrate your question, the key to the answer might be here: "The a axis, perpendicular to the chains in the structure, is the magnetic easy axis, while the ...
  • 1,421
9 votes

How accurately are magnetic effects treated in *ab initio* methods?

It is an example where representative of different fields would give you very different answers. I do not want to pretend my answer would be by anyway complete. Short answer: yes. And the devil, as ...
  • 1,657
9 votes
Accepted

How to perform HSEsol in VASP calculations?

You want the following flags in your INCAR to specify HSEsol: GGA = PS LHFCALC = .TRUE. HFSCREEN = 0.2 I also recommend setting ...
  • 6,971
8 votes
Accepted

What are examples of materials that closely correspond to the Heisenberg model?

1D A famous example of a nearly ideal spin-$1/2$ isotropic Heisenberg antiferromagnetic chain (1D) system is copper pyrazine dinitrate [Cu(C$_4$H$_4$N$_2$)(NO$_3$)$_2$], which was discussed in Hammar ...
  • 4,403
8 votes

Ising model: How can I spot the critical point?

I think Anyon's and taciteloquence's answers are perfect. I just want to add an emphasis on the following fact that frequently leads to confusion for beginners. The formal definition of the ...
8 votes
Accepted

Getting different total magnetic moment in 'scf' and 'vc-relax' calculations in Quantum ESPRESSO

Looking at your input and output files, I think the most likely explanation is a different local minimum in the energy, as mentioned by Andrew in the comments. If you look at the final scf step in the ...
  • 2,931
8 votes

Getting different total magnetic moment in 'scf' and 'vc-relax' calculations in Quantum ESPRESSO

Edit: This no longer seems to be the issue, as the atomic positions are apparently essentially unchanged, per @KevinJ.M.'s comment. I will nonetheless keep the answer here because it is still ...
  • 6,971
7 votes

Predicting magnetic moment of a metal complex computationally

The main question here is whether the question makes sense for ${\rm K}_3[{\rm Mn(CN)}_6]$ as a molecular complex. Looks like the material has a solid state structure https://materials.springer.com/...
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7 votes
Accepted

How to do spin polarization calculations using Quantum ESPRESSO?

First, I would recommend reading through the pw.scf input file description, provided here. The relevant parameters are in the &SYSTEM namelist of the input file. To do a basic, linear spin-...
  • 2,931
7 votes

Magnetism and Topology

Topological magnon band structures Another way of combining topology and magnetism is to consider a magnetic insulator with non-trivial magnon band structure. This setting is somewhat different from ...
  • 4,403
7 votes
Accepted

Is the "Final Magnetic moment" in the materials project repository same as the "total magnetization" value in Quantum ESPRESSO output files?

With the Materials Project and magnetism, it's often useful to download the structure directly and examine the magnetic moments on that structure, for example using the pymatgen Python code and the <...
  • 1,471
6 votes

What measured quantity can be associated to the value of the J parameter in the Heisenberg/Ising hamiltonians?

Here I'll assume that the material is already believed to be roughly described by a model of the Heisenberg or Ising form. In that case, you just want a quantity that is easy to measure in your ...

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