Electrical and vibrational properties of hydrogen bonds in glycinewater clusters

摘要

The hydrogen bond (H-bond) in organic-water molecules is essential in nature. Combining with the charge - transferanalyses, we investigated the penetrating molecular-orbitals in glycine-water clusters, which give evidences of thecovalent-like characteristics of H-bonds in this system. Besides, the infrared spectral features provide a rare opportunityto discover the exceedingly-evident redshifts of symmetric stretching modes (Symst) in water on forming H-bond, incontrast to the slightly-redshifted asymmetric stretching modes (Asyst) in water. To explain these intriguing behaviors,we further analyzed the nuclear vibrating patterns, which clearly reveal that H-bond retains two unexpected effects onnuclear motions in water: (ⅰ) Intensifying donor Symst, and (ⅱ) Inhibiting donor Asyst. Furthermore, we also quantifiedthe impact of anharmonic quantum fluctuations on each hydrogen bond. For the stretching modes involved in H-bonds,red shifts up to more than one hundred wave numbers are observed under anharmonic vibration, explicitly indicating theincreased ‘covalency’ of H-bonds. These finds shed light on the essential understanding of H-bonding comprehensively,and should provide incentives for future experimental studies.