Exact Combinatorial Density of States for the Critical 1D Ising Model

Fuente: arXiv
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Auteurs principaux: Castorene, Bastian, Peña, Francisco J., Groves, Martin HvE, Vargas, Patricio
Format: Preprint
Publié: 2025
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author Castorene, Bastian
Peña, Francisco J.
Groves, Martin HvE
Vargas, Patricio
author_facet Castorene, Bastian
Peña, Francisco J.
Groves, Martin HvE
Vargas, Patricio
contents This work presents an exact microcanonical combinatorial analysis of the one-dimensional antiferromagnetic Ising model. At the primary ground-state level crossing $B/J=2$, degeneracies follow the Fibonacci and Lucas sequences for open chains and periodic rings, respectively. We extend this framework to the complete excitation spectrum, demonstrating that the density of states is constructed from topological defects governed by linear Diophantine equations and $p$-fold Fibonacci convolutions. Open boundaries act as fractional defects, densifying the chain spectrum into energy steps of $2J$, whereas the closed ring remains quantized in units of $4J$. Notably, this exact topological counting exposes non-trivial spectral gaps near the fully polarized limit, strictly forbidding the penultimate macroscopic energy levels in both topologies. Through the transfer matrix formalism, we derive exact closed-form expressions for the critical degeneracies at all energy levels. These results provide a rigorous analytical foundation for extracting exact residual entropies and exposing the intrinsic number-theoretic architecture of quantum critical manifolds.
format Preprint
id arxiv_https___arxiv_org_abs_2511_01646
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Exact Combinatorial Density of States for the Critical 1D Ising Model
Castorene, Bastian
Peña, Francisco J.
Groves, Martin HvE
Vargas, Patricio
Statistical Mechanics
Quantum Physics
This work presents an exact microcanonical combinatorial analysis of the one-dimensional antiferromagnetic Ising model. At the primary ground-state level crossing $B/J=2$, degeneracies follow the Fibonacci and Lucas sequences for open chains and periodic rings, respectively. We extend this framework to the complete excitation spectrum, demonstrating that the density of states is constructed from topological defects governed by linear Diophantine equations and $p$-fold Fibonacci convolutions. Open boundaries act as fractional defects, densifying the chain spectrum into energy steps of $2J$, whereas the closed ring remains quantized in units of $4J$. Notably, this exact topological counting exposes non-trivial spectral gaps near the fully polarized limit, strictly forbidding the penultimate macroscopic energy levels in both topologies. Through the transfer matrix formalism, we derive exact closed-form expressions for the critical degeneracies at all energy levels. These results provide a rigorous analytical foundation for extracting exact residual entropies and exposing the intrinsic number-theoretic architecture of quantum critical manifolds.
title Exact Combinatorial Density of States for the Critical 1D Ising Model
topic Statistical Mechanics
Quantum Physics
url https://arxiv.org/abs/2511.01646