Identification and Optimization of Accurate Spin Models for Open-Shell Carbon Ladders with Matrix Product States
- URL: http://arxiv.org/abs/2512.18695v1
- Date: Sun, 21 Dec 2025 11:16:10 GMT
- Title: Identification and Optimization of Accurate Spin Models for Open-Shell Carbon Ladders with Matrix Product States
- Authors: Andoni Agirre, Thomas Frederiksen, Geza Giedke, Tobias Grass,
- Abstract summary: Open-shell nanographenes offer a controlled setting to study correlated magnetism emerging from $$-electron systems.<n>We analyze oligo(indenoindene) molecules, non-bipartite carbon ladders whose tight-binding spectra feature a gapped, weakly dispersing manifold of quasi-zero modes, and show that their low-energy properties can be effectively mapped onto an interacting set of spin-1/2 degrees of freedom.
- Score: 0.1749935196721634
- License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
- Abstract: Open-shell nanographenes offer a controlled setting to study correlated magnetism emerging from $π$-electron systems. We analyze oligo(indenoindene) molecules, non-bipartite carbon ladders whose tight-binding spectra feature a gapped, weakly dispersing manifold of quasi-zero modes, and show that their low-energy properties can be effectively mapped onto an interacting set of spin-1/2 degrees of freedom. Using Density Matrix Renormalization Group simulations of the full Fermi-Hubbard model, we obtain their excitation spectra, entanglement profiles, and spin-spin correlations. We then construct optimized delocalized fermionic modes that act as emergent spins and show that their interactions are well described by a frustrated $J_1$-$J_2$ Heisenberg chain. This effective description clarifies how spin degrees of freedom arise and interact in non-bipartite nanographene ladders, providing a compact and accurate representation of their correlated behavior.
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