Rotational excitation cross sections of para-H2+para-H2 collisions. A full-dimensional wave-packet propagation study using an exact form of the kinetic energy

Abstract

A full-dimensional quantum dynamical study of the rotational excitation in para-para H2 + H2 collisions using the potential-energy surface of Boothroyd et al. [J. Chem. Phys. 116, 666 (2002)] is reported. The multiconfiguration time-dependent Hartree algorithm is utilized to propagate wave packets and the cross sections for collision energies up to 1.2 eV are determined by a flux analysis through the interaction of the wave packet with a complex absorbing potential. Calculations for a collection of total angular momenta up to J = 70 are performed; the missing channels are obtained with a J-interpolation algorithm.

Rotational energy transfer in H2+H2

“…The investigation of elastic and inelastic collisions between molecules and between molecules and atoms can provide valuable information about interactions, chemical properties and energy transfer dynamics [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. The hydrogen molecule is the simplest and most abundant molecule in the universe's molecular clouds and plays an important role in many areas of astrophysics.…”

The molecular Hamiltonian with two-rotational-angle embedding

“…Introducing these position vectors into equations (23b) and (23c), making use of equation (23a) [For the three-rotational-angle embedding case the indices , in equations (23a)-(23c), (24), (25) and (42) go over x , y as well as z.] and solving the resulting equations for the components of vector x i f (i ¼ 1, .…”

On direct product based discrete variable representations for angular coordinates and the treatment of singular terms in the kinetic energy operator

“…[29,30]) by an incomplete separation of the overall rotation. Separating only two instead of three Euler angles from the internal coordinates (as typically done for linear molecules), only singularities of the type 1= sin 2 h i @ 2 @/ 2 i appear and direct products of two-dimensional FBRs for each h i , / i pair can be used.…”