Ab initio calculation of the dynamical properties of PPP and PPV

TL;DR

This paper uses ab initio methods to calculate vibrational properties and thermodynamic behaviors of crystalline PPP and PPV, providing insights into their stability and agreement with experimental data.

Contribution

It presents the first ab initio calculations of vibrational modes, frequencies, and thermodynamic properties for specific crystalline forms of PPP and PPV.

Findings

Vibrational frequencies agree with experimental data

PPP is more stable in Pnnm structure at high temperatures

Calculated thermodynamic properties show temperature dependence

Abstract

In this work, we have calculated the vibrational modes and frequencies of the crystalline PPP (in both the Pbam and Pnnm symmetries) and PPV (in the P21/c symmetry). Our results are in good agreement with the available experimental data. Also, we have calculated the temperature dependence of their specific heats at constant volume, and of their vibrational entropies. Based on our results, at high temperatures, the PPP is more stable in the Pnnm structure than in the Pbam one.