Elastic constants and thermodynamics properties of pristine PEDOT revealed: A first-principles PBE/PBE PAW approach

TL;DR

This study uses first-principles DFT calculations to determine the elastic and thermodynamic properties of pristine PEDOT, revealing its stable monoclinic structure and detailed elastic constants, with implications for its material characteristics.

Contribution

First-principles PBE/PBEsol-PAW calculations of PEDOT's elastic and thermodynamic properties, providing detailed insights into its stable structure and mechanical behavior.

Findings

Identified the monoclinic structure as the most stable form of PEDOT.

Calculated thirteen independent elastic constants and derived related properties.

Predicted Debye temperature and specific heat capacity consistent with theoretical models.

Abstract

In this work, we report for the first time, detailed calculations of elastic and thermodynamic properties of organic poly(3,4-ethylenedioxythiophene), PEDOT, in an undiluted state, using PBE and PBEsol-PAW pseudopotentials within the framework of Generalized Gradient Approximation Density Functional Theory. Contrary to Molecular Dynamic simulations, series of PBE and PBEsol-PAW calculations in the current work revealed the most stable state of monoclinic structured pristine PEDOT. We determined thirteen (13) independent elastic constants with elastic compliance which enables us to establish other elastic properties of pristine PEDOT; the Pugh's ratio and the Vicker's hardness calculations show small mismatches with PBE and PBEsol-PAW pseudopotentials. The Debye temperature TD is predicted both in the PBE and PBEsol-PAW calculations while the specific heat capacity Cv(T) follows the Dulong-Petit curve having no mismatch with Debye model at low temperature, with PBE predicting a higher Debye sound velocity than PBEsol-PAW. As accuracy tests only, we performed electronic structure calculations of PEDOT and compared with available data in the literature.