A crossover from a non-Gaussian to Gaussian sub-diffusion has been observed ubiquitously in various polymeric/molecular glass-formers. We have developed a framework which generalizes the fractional Brownian motion (fBm) model to incorporate non-Gaussian features by introducing a jump kernel. We illustrate that the non-Gaussian fBm (nGfBm) model accurately characterizes the sub-diffusion crossover. From the solutions of the nGfBm model, we gain insights into the nature of van-Hove self-correlation in non-Gaussian subdiffusive regime, which are found to exhibit exponential tails, providing first such experimental evidence in molecular and polymeric glass-formers. The results of the model are substantiated using incoherent quasielastic neutron scattering on glass-forming deep eutectic solvents.
@article{arxiv.2303.07870,
title = {Nature of Sub-diffusion Crossover in Molecular and Polymeric Glass-Formers},
author = {H. Srinivasan and V. K. Sharma and V. G. Sakai and S. Mitra},
journal= {arXiv preprint arXiv:2303.07870},
year = {2024}
}