title: Polarization response of clathrate hydrates capsulated with guest molecules.
abstract: Clathrate hydrates are characterized by their water cages encapsulating various guest atoms or molecules. The polarization effect of these guest-cage complexes was studied with combined density functional theory and finite-field calculations. An addition rule was noted for these systems whose total polarizability is approximately equal to the polarizability sum of the guest and the cage. However, their distributional polarizability computed with Hirshfeld partitioning scheme indicates that the guest-cage interaction has considerable influence on their polarization response. The polarization of encapsulated guest is reduced while the polarization of water cage is enhanced. The counteraction of these two opposite effects leads to the almost unchanged total polarizability. Further analysis reveals that the reduced polarizability of encapsulated guest results from the shielding effect of water cage against the external field and the enhanced polarizability of water cage from the enhanced bonding of hydrogen bonds among water molecules. Although the charge transfer through the hydrogen bonds is rather small in the water cage, the polarization response of clathrate hydrates is sensitive to the changes of hydrogen bonding strength. The guest encapsulation strengthens the hydrogen bonding network and leads to enhanced polarizability.
authors.affiliation: Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), Mianyang 621900, China.
authors.forename: Qun
authors.initials: Q
authors.lastname: Zeng
authors.affiliation: Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), Mianyang 621900, China.
authors.forename: Jinshan
authors.initials: J
authors.lastname: Li
authors.affiliation: Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), Mianyang 621900, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Huang
authors.affiliation: Institute of Atomic and Molecular Physics, Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610065, People's Republic of China.
authors.forename: Xinqin
authors.initials: X
authors.lastname: Wang
authors.affiliation: Institute of Atomic and Molecular Physics, Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610065, People's Republic of China.
authors.forename: Mingli
authors.initials: M
authors.lastname: Yang