title: Impact of the Condensed-Phase Environment on the Translation-Rotation Eigenstates and Spectra of a Hydrogen Molecule in Clathrate Hydrates.
abstract: We systematically investigate the manifestations of the condensed-phase environment of the structure II clathrate hydrate in the translation-rotation (TR) dynamics and the inelastic neutron scattering (INS) spectra of an H2 molecule confined in the small dodecahedral cage of the hydrate. The aim is to elucidate the extent to which these properties are affected by the clathrate water molecules beyond the confining cage and the proton disorder of the water framework. For this purpose, quantum calculations of the TR eigenstates and INS spectra are performed for H2 inside spherical clathrate domains of gradually increasing radius and the number of water molecules ranging from 20 for the isolated small cage to more than 1800. For each domain size, several hundred distinct hydrogen-bonding topologies are constructed in order to simulate the effects of the proton disorder. Our study reveals that the clathrate-induced splittings of the j = 1 rotational level and the translational fundamental of the guest H2 are influenced by the condensed-phase environment to a dramatically different degree, the former very strongly and the latter only weakly.
authors.affiliation: Department of Chemistry, New York University , New York, New York 10003, United States.
authors.forename: Anna
authors.initials: A
authors.lastname: Powers
authors.affiliation: Department of Chemistry, New York University , New York, New York 10003, United States.
authors.forename: Ondrej
authors.initials: O
authors.lastname: Marsalek
authors.affiliation: Department of Chemistry, New York University , New York, New York 10003, United States.
authors.forename: Minzhong
authors.initials: M
authors.lastname: Xu
authors.affiliation: Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi , Via Madonna del Piano 10, I-50019, Sesto Fiorentino, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Ulivi
authors.affiliation: Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi , Via Madonna del Piano 10, I-50019, Sesto Fiorentino, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Colognesi
authors.affiliation: Department of Chemistry and Courant Institute of Mathematical Sciences, New York University , New York, New York 10003, United States.|NYU-ECNU Center for Computational Chemistry at NYU Shanghai , 3663 Zhongshan Road North, Shanghai, 200062, China.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Tuckerman
authors.affiliation: Department of Chemistry, New York University , New York, New York 10003, United States.|NYU-ECNU Center for Computational Chemistry at NYU Shanghai , 3663 Zhongshan Road North, Shanghai, 200062, China.
authors.forename: Zlatko
authors.initials: Z
authors.lastname: Bačić
mesh_terms: D006859:Hydrogen / Q000737:chemistry*; D008956:Models, Chemical; D013057:Spectrum Analysis; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D006859:Hydrogen