Simulating Relaxation Channels of CO2 in Clathrate Nanocages

5th International Conference on Mathematical Modeling in Physical Sciences

物理学;数学

Dahoo, P.R.^1,2 ; Puig, R.^2 ; Lakhlifi, A.^3 ; Meis, C.^2,4 ; Gale, J.D.^2,5

LATMOS/IPSL, UVSQ Université Paris-Saclay, UPMC Univ. Paris 06, CNRS, Guyancourt

F-78280, France^1

CHAIR Materials Simulation and Engineering, UVSQ, Université Paris Saclay, Versailles Cedex

78035, France^2

Institut UTINAM-UMR 6213 CNRS, Université de Franche-Comté, Observatoire de Besançon, Besançon Cedex

25010, France^3

INSTN- CEA, Université Paris Saclay, Gif-sur-Yvette

91191, France^4

Nanochemistry Research Institute, Curtin Institute for Computation, Department of Chemistry, Curtin University, PO Box U1987, Perth

WA

6845, Australia^5

关键词: Atom-atom interaction;    Born-Oppenheimer approximation;    Harmonic frequency;    High-frequency vibrational modes;    Large-amplitude motion;    Librational modes;    Relaxation channels;    Small amplitude;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/738/1/012072/pdf
DOI  :  10.1088/1742-6596/738/1/012072

来源: IOP

【 摘 要 】

The energy levels of CO2in the small (s) and large (l) nano-cages of cubic sI clathrates are calculated in the Born-Oppenheimer approximation using pairwise atom-atom interaction potentials. In the s cage, the centre of mass of CO2oscillates with small amplitudes, asymmetrically about the cage center with harmonic frequencies around 100 cm-1. In the l cage, oscillations are anharmonic with large amplitude motions in a plane parallel to the hexagonal faces of the cage and the corresponding frequencies are calculated to be 55 cm-1and 30 cm-1. Librational harmonic frequencies are calculated at 101.7 cm-1and 56.0 cm-1in the 5 cage and at 27.9 cm-1and 46.4 cm-1in the l cage. Results show that the coupling between the CO2molecule and the nano-cage is quite different for the low frequency translational, rotational or librational modes and the high frequency vibrational modes, which consequently leads to different relaxation channels.