Hankel Marlies, Smith Sean C, Allan Robert J, Gray Stephen K, Balint-Kurti Gabriel G
Centre for Computational Molecular Science, The University of Queensland, Queensland QLD 4072, Australia.
J Chem Phys. 2006 Oct 28;125(16):164303. doi: 10.1063/1.2358350.
State-to-state differential cross sections have been calculated for the hydrogen exchange reaction, H+H2-->H2+H, using five different high quality potential energy surfaces with the objective of examining the sensitivity of these detailed cross sections to the underlying potential energy surfaces. The calculations were performed using a new parallel computer code, DIFFREALWAVE. The code is based on the real wavepacket approach of Gray and Balint-Kurti [J. Chem. Phys. 108, 950 (1998)]. The calculations are parallelized over the helicity quantum number Omega' (i.e., the quantum number for the body-fixed z component of the total angular momentum) and wavepackets for each J,Omega' set are assigned to different processors, similar in spirit to the Coriolis-coupled processors approach of Goldfield and Gray [Comput. Phys. Commun. 84, 1 (1996)]. Calculations for J=0-24 have been performed to obtain converged state-to-state differential cross sections in the energy range from 0.4 to 1.2 eV. The calculations employ five different potential energy surfaces, the BKMP2 surface and a hierarchical family of four new ab initio surfaces [S. L. Mielke, et al., J. Chem. Phys. 116, 4142 (2002)]. This family of four surfaces has been calculated using three different hierarchical sets of basis functions and also an extrapolation to the complete basis set limit, the so called CCI surface. The CCI surface is the most accurate surface for the H3 system reported to date. Our calculations of differential cross sections are the first to be reported for the A2, A3, A4, and CCI surfaces. They show that there are some small differences in the cross sections obtained from the five different surfaces, particularly at higher energies. The calculations also show that the BKMP2 performs well and gives cross sections in very good agreement with the results from the CCI surface, displaying only small divergences at higher energies.
已使用五个不同的高质量势能面计算了氢交换反应H + H₂→H₂ + H的态-态微分截面，目的是检验这些详细截面对于基础势能面的敏感性。计算使用了一种新的并行计算机代码DIFFREALWAVE来执行。该代码基于Gray和Balint-Kurti的实波包方法[《化学物理杂志》108, 950 (1998)]。计算在螺旋度量子数Ω′（即总角动量在体固定z分量的量子数）上进行并行化，并且为每个J,Ω′集的波包分配给不同的处理器，这在精神上类似于Goldfield和Gray的科里奥利耦合处理器方法[《计算物理通讯》84, 1 (1996)]。已对J = 0 - 24进行了计算，以在0.4至1.2 eV的能量范围内获得收敛的态-态微分截面。计算采用了五个不同的势能面，即BKMP2面和一个由四个新的从头算面组成的层次族[S. L. Mielke等人，《化学物理杂志》116, 4142 (2002)]。这四个面的族已使用三种不同层次的基函数集进行计算，并且还外推到了完全基集极限，即所谓的CCI面。CCI面是迄今为止报道的H₃系统最精确的面。我们对微分截面的计算是首次针对A2、A3、A4和CCI面进行报道。结果表明，从五个不同面获得的截面存在一些小差异，特别是在较高能量时。计算还表明，BKMP2表现良好，给出的截面与CCI面的结果非常吻合，仅在较高能量时显示出小的偏差。
