# Theoretical Characterization of Structural Disorder in the Tetramer Model Structure of Eumelanin

## TL;DR

This paper develops a piecewise Ising Model to predict formation enthalpies of eumelanin tetramers, offering a new theoretical approach to understanding its complex disorder and properties.

## Contribution

The work introduces a modular Ising Model for eumelanin, enabling detailed energetic landscape analysis and extending to larger polymer structures.

## Key findings

- Superior predictive accuracy of the Ising Model for tetramer formation enthalpies
- Potential to analyze larger eumelanin structures like hexamers and octomers
- Framework for integrating absorbance data with polymer abundance predictions

## Abstract

Eumelanin is regarded to be an attractive candidate material for biomedical applications. Despite many theoretical studies exploring the structure of eumelanin, an exact mapping of the energetic landscape of the very large phase space of eumelanin is still elusive. In this work, we implement a piecewise Ising Model to predict formation enthalpies of Eumelanin single and double tetramers, and demonstrate its superior predictive and generalizable capabilities. We believe this model will prove very useful in theoretically characterizing the many unique properties attributed to its disorder. The modular nature of the predictive Ising model built up in this work is well-suited for analysis and characterization of a larger phase space of eumelanin polymers, including hexamers and octomers, as well as larger stacked structures, such as potential triple and quadruple eumelanin tetramers. Absorbance data can be incorporated with population-wide predictions of polymer abundance to produce weighted-average predictions of broadband absorbance of bulk eumelanin.