Quantum dynamics of rovibrational transitions in H2-H2 collisions: Internal energy and rotational angular momentum conservation effects

被引:47
作者
dos Santos, S. Fonseca [1 ]
Balakrishnan, N. [1 ]
Lepp, S. [2 ]
Quemener, G. [3 ,4 ]
Forrey, R. C. [5 ]
Hinde, R. J. [6 ]
Stancil, P. C. [7 ,8 ]
机构
[1] Univ Nevada, Dept Chem, Las Vegas, NV 89154 USA
[2] Univ Nevada, Dept Phys, Las Vegas, NV 89154 USA
[3] Univ Colorado, JILA, Boulder, CO 80309 USA
[4] NIST, Boulder, CO 80309 USA
[5] Penn State Univ, Dept Phys, Reading, PA 19610 USA
[6] Univ Tennessee, Dept Chem, Knoxville, TN 37996 USA
[7] Univ Georgia, Dept Phys & Astron, Athens, GA 30602 USA
[8] Univ Georgia, Ctr Simulat Phys, Athens, GA 30602 USA
基金
美国国家科学基金会;
关键词
LOG-DERIVATIVE METHOD; VIBRATIONAL-RELAXATION; CHEMICAL-REACTIONS; LOW-TEMPERATURE; STATE; SCATTERING; MOLECULES; H-2; H-2-MOLECULES; EXCITATION;
D O I
10.1063/1.3595134
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
We present a full dimensional quantum mechanical treatment of collisions between two H-2 molecules over a wide range of energies. Elastic and state-to-state inelastic cross sections for ortho-H-2 + para-H-2 and ortho-H-2 + ortho-H-2 collisions have been computed for different initial rovibrational levels of the molecules. For rovibrationally excited molecules, it has been found that state-to-state transitions are highly specific. Inelastic collisions that conserve the total rotational angular momentum of the diatoms and that involve small changes in the internal energy are found to be highly efficient. The effectiveness of these quasiresonant processes increases with decreasing collision energy and they become highly state-selective at ultracold temperatures. They are found to be more dominant for rotational energy exchange than for vibrational transitions. For non-reactive collisions between ortho- and para-H-2 molecules for which rotational energy exchange is forbidden, the quasiresonant mechanism involves a purely vibrational energy transfer albeit with less efficiency. When inelastic collisions are dominated by a quasiresonant transition calculations using a reduced basis set involving only the quasiresonant channels yield nearly identical results as the full basis set calculation leading to dramatic savings in computational cost. (c) 2011 American Institute of Physics. [doi:10.1063/1.3595134]
引用
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页数:11
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