Ab initio molecular dynamics of ionic liquids under pressure

Abstract

The understanding of physico-chemical properties of ionic liquids at molecular level by theoretical and experimental works aims the predicting ability of properties of new systems. Vibrational spectroscopy is a powerful technique to study both structure and dynamics of ionic liquids, and ab initio calculations of small clusters are largely used to help interpreting the experimental spectra. Classical molecular dynamics simulation, which demands a previously parameterized effective potential energy function, is also a common tool to study ionic liquids. The use of ab initio molecular dynamics (AIMD) to calculate vibrational spectra can provide further information as AIMD takes into account the molecular electronic structure. Vibrational spectra of liquids under high pressure exhibit frequency shifts and changes on band shapes resulting from coupling between the intra and intermolecular dynamics. The aim of this project is to calculate vibrational spectra of ionic liquids under high pressure by AIMD simulations and compare it to experimental spectra. The calculation of vibrational spectra by AIMD will require a study of DFT performance under high pressure by using small clusters in order to test different functionals and their response within the short range of the potential energy. Then, the AIMD simulations under high pressure will be performed and vibrational spectra obtained by Fourier transforming the appropriate time correlation functions. (AU)