# Questions tagged [heisenberg-model]

For questions related to the Heisenberg model Hamiltonian.

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I consider that $H$ is a Hamiltonian describing a quantum system of $n$ spin-1/2 particles (or qubits). I assume it can be written as (the $\alpha_k^i$ are real coefficients): $$\tag{1}H=\sum_{i=1}^3 ... 8 votes 1 answer 226 views ### What's the most efficient way to obtain the ground state of spin models exactly? (Note: an earlier version of this question had been asked on Phys.SE before) It is known that finding the ground state of classical spin glasses is NP-hard: it will take (at least) an exponential ... • 333 13 votes 3 answers 368 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 ... • 4,458 14 votes 1 answer 189 views ### How to choose the values of J and spin parameters in a heterogeneous spin system? In this work, graphene-based systems that are described by mixed spin-3/2 and spin-5/2 are studied using the ising-model. A diagram of the structure is shown bellow: The Hamiltonian used is: \begin{... • 22.9k 18 votes 2 answers 1k 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,... • 22.9k 8 votes 1 answer 137 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 ... • 22.9k 9 votes 3 answers 328 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): \tag{Heisenberg} \hat{H}... • 22.9k 15 votes 1 answer 694 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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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 ...