LAUSR

Abstract Weak interactions dominate chemical interactions between a protein and a drug, or a catalyst and its substrate, self-assembly of nanomaterials, and even some chemical reactions. It is importance to investigate and understand weak interactions. In this work, we reported an approach combining terahertz time domain spectroscopy (THz-TDS) with quantum chemistry tools to investigate the intermolecular weak interaction. Firstly, the imidacloprid four molecular clusters structure and absorption spectrum was calculated by using density functional theoretical (DFT). The calculation absorption peaks are consistent with the experimental result. And then the intermolecular weak interaction were qualitatively and quantitatively investigated by using independent gradient model (IGM) and energy decomposition analysis (EDA). The results show that van der Waals interactions and weak hydrogen bonds play a crucial role contribution to intermolecular weak interaction of imidacloprid. Thus, combining THz-TDS with DFT, IGM and EDA-FF is a powerful tool for investigation the intermolecular weak interaction.