The radical character of the acenes: A density matrix renormalization group study

TL;DR

This study uses advanced computational methods to analyze the electronic structure of acenes, revealing that longer acenes exhibit polyradical character, which impacts their chemical properties.

Contribution

The paper applies a high-level density matrix renormalization group approach to accurately characterize the radical nature of acenes from naphthalene to dodecacene.

Findings

Longer acenes are polyradical in nature.

Ground state remains a singlet across all chain lengths.

Multiple measures confirm radical character in extended acenes.

Abstract

We present a detailed investigation of the acene series using high-level wavefunction theory. Our ab-initio Density Matrix Renormalization Group algorithm has enabled us to carry out Complete Active Space calculations on the acenes from napthalene to dodecacene correlating the full pi-valence space. While we find that the ground-state is a singlet for all chain-lengths, examination of several measures of radical character, including the natural orbitals, effective number of unpaired electrons, and various correlation functions, suggests that the longer acene ground-states are polyradical in nature.