Questions tagged [spin-models]

Questions related to spin models wrt materials modeling.

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6
votes
1answer
47 views

How to choose starting magnetization while doing spin polarised calculation in Quantum ESPRESSO?

I am trying to run spin polarised DFT calculation in Quantum ESPRESSO on system Co2MnSi. I kept starting magnetization for all these three species as, ...
11
votes
1answer
91 views

Ising models with many-body interactions

I find it surprisingly difficult to find researches/papers on systematic "many-body interaction" extensions of the Ising model. Can somebody tell me a good review/article etc on this matter ...
6
votes
0answers
29 views

How to choose the values of J and spin parameters in a heterogeneous spin system?

Previous questions (here, here and here) were about modeling magnetic homogeneous systems using Heisenberg and/or Ising hamiltonians: \begin{equation} \tag{Heisenberg} \hat{H}_H=-\sum_{\langle i j\...
13
votes
2answers
277 views

What are good random number generators for Monte Carlo calculations?

Many problems in Computational Physics need the use of random number generators. When studying magnetic materials using the Heisenberg/Ising hamiltonians (related questions about them can be seen here,...
5
votes
1answer
66 views

What measured quantity can be associated to the value of the J parameter in the Heisengerg/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 Heisengerg/Ising hamiltonians? Here J is the ...
6
votes
0answers
76 views

Is it possible to calculate/estimate the value of the J parameter to be used in the Heisengerg/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}...
12
votes
2answers
116 views

Autocorrelation function problem in Monte Carlo simulation of 2D Ising model

Currently, I did a Monte Carlo simulation with the local update and Wolff cluster updated in 2D classical Ising model. I use the autocorrelation function to compare 2 different algorithm in critical ...
15
votes
2answers
62 views

Is there a list of models that do and do not have the QMC sign problem?

The sign problem is a huge limitation of QMC, but it's not easy to tell by looking at a Hamiltonian if it has the sign problem. Often there will be some clever transformation that allows you to avoid ...
22
votes
3answers
154 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 ...