title: Resolving the Origins of Crystalline Anharmonicity Using Terahertz Time-Domain Spectroscopy and ab Initio Simulations.
abstract: Anharmonicity has been shown to be an important piece of the fundamental framework that dictates numerous observable phenomena. In particular, anharmonicity is the driving force of vibrational relaxation processes, mechanisms that are integral to the proper function of numerous chemical processes. However, elucidating its origins has proven difficult due to experimental and theoretical challenges, specifically related to separating the anharmonic contributions from other unrelated effects. While no one technique is particularly suited for providing a complete picture of anharmonicity, by combining multiple complementary methods such a characterization can be made. In this study the role of individual atomic interactions on the anharmonic properties of crystalline purine, the building block of many DNA and RNA nucleobases, is studied by experimental terahertz time-domain spectroscopy and first-principles density functional theory (DFT) and ab initio molecular dynamics simulations (AIMD). In particular, the detailed vibrational information provided by the DFT calculations is used to interpret the atomic origins of anharmonic-related effects as determined by the AIMD calculations, which are in good agreement with the experimental data. The results highlight that anharmonicity is especially pronounced in the intermolecular interactions, particularly along the amine hydrogen bond coordinate, and yields valuable insight into what is similarly observed complex biosystems and crystalline solids.
authors: Department of Chemical Engineering and Biotechnology, University of Cambridge , Philippa Fawcett Drive, Cambridge CB3 0AS, United Kingdom.
authors: Michael T
authors: MT
authors: Ruggiero
authors: Department of Chemical Engineering and Biotechnology, University of Cambridge , Philippa Fawcett Drive, Cambridge CB3 0AS, United Kingdom.
authors: J Axel
authors: JA
authors: Zeitler
mesh_terms: D000588:Amines / Q000737:chemistry*; D003460:Crystallization; D056004:Molecular Dynamics Simulation; D011789:Quantum Theory; D055068:Terahertz Spectroscopy; D013997:Time Factors
chemical_list: D000588:Amines