The Effect of Spatial Correlation on Liquid Phase Vibrational Spectra

Within this project, the influence of spatial correlation on the vibrational spectra (infrared, Raman, VCD, ROA) of condensed phase systems shall be investigated. It is well known in the literature that spatial correlation plays a significant role for the signal intensity in vibrational spectroscopy, but there does not yet exist a generally applicable protocol to study such phenomena computationally. Developing such an approach is not only of theoretical value, but will significantly help to better understand and complement experimental vibrational spectra. To reach this goal, we will build upon existing methods for predicting liquid phase vibrational spectra from ab initio simulations that we have developed in the past, such as the Voronoi integration method. By selectively including certain cross-correlation terms between molecules depending on their distance, we will shed light on the role of spatial correlation in solid and liquid systems. Going one step further, it will even become possible to go beyond the definition of molecules (which is sometimes ambiguous, such as in complexes and supramolecular assemblies), so that spectra can directly be obtained from cross-correlation terms between individual atoms.

DFG Programme Research Grants