Quantum dynamics of a hydrogen molecule confined in a cylindrical potential

2019-12-23 08:52:51

potential hydrogen dynamics H2 molecule

责任者: Yildirim, T.;Harris, A.B. 单位: Nat. Inst. of Stand. & Technol., Gaithersburg, MD, USA 来源出处: Physical Review B (Condensed Matter and Materials Physics)(Phys. Rev., B, Condens, Matter Mater. Phys. (USA)),2003/06/15,67(24):245413-1 摘要: We study the coupled rotation-vibration levels of a hydrogen molecule in a confining potential with cylindrical symmetry. We include the coupling between rotations and translations and show how this interaction is essential to obtain the correct degeneracies of the energy level scheme. We applied our formalism to study the dynamics of H2 molecules inside a smooth carbon nanotube as a function of tube radius. The results are obtained both by numerical solution of the (2J+1)-component radial Schrodinger equation and by developing an effective Hamiltonian to describe the splitting of a manifold of states of fixed angular momentum J and number of phonons N. For nanotube radius smaller than ≈3.5 Å, the confining potential has a parabolic shape and the results can be understood in terms of a simple toy model. For larger radius, the potential has the Mexican hat shape and therefore the H2 molecule is off centered, yielding radial and tangential translational dynamics in addition to rotational dynamics of H2 molecule which we also describe by a simple model. Finally, we make several predictions for the the neutron scattering observation of various transitions between these levels 关键词: carbon nanotubes;hydrogen neutral molecules;neutron diffraction;phonons;potential energy functions;rotational-vibrational states;Schrodinger equation;translational states;quantum dynamics;hydrogen molecule;cylindrical potential;coupled rotation-vibration levels;confining potential;cylindrical symmetry;rotations;translations;energy level scheme;carbon nanotube;tube radius;numerical solution;(2J+ l)-component radial Schrodinger equation;effective Hamiltonian;splitting;fixed angular momentum;phonons;simple toy model;Mexican hat shape potential;radial translational dynamics;tangential translational dynamics;rotational dynamics;neutron scattering;3.5 Å;C:H2