---
author:
- 'S. [Ö]{}ttl'
- 'S. E. Huber'
- 'S. Kimeswenger'
- 'M. Probst'
date: 'Received 16 June 2014; accepted 15 July 2014'
subtitle: 'Infrared spectra, energetics and alternative formation pathways'
title: 'Coronene and pyrene (5, 7)-member ring defects'
---

[We present a theoretical study of the IR spectra of PAHs containing (5, 7)-member ring defects, focusing on pyrene ($C_{16}H_{10}$) and coronene ($C_{24}H_{12}$).]{} [Using density functional theory, we investigate the effects of such defects on the IR spectra of pyrene and coronene and their cations and anions. In addition, we explore parts of the potential energy surface of the neutral species and discuss alternative formation pathways. ]{} [The addition of (5, 7)-membered ring defects in pyrene and coronene results in a change of the IR spectra, both molecules loose their typical spectroscopic signature. We find shifts in the positions of the band as well as different intensities and a rise in the number of features. The boundaries in terms of the size of the PAHs exhibiting a (5, 7)-membered ring defect are studied and shown. Investigation of the minimal energy pathway leads to a result of 8.21 eV for pyrene and 8.41 eV for coronene as minimum activation barriers 