Domínguez Juan C, Silva Eivson D, Pimbi Daniel, Morales Jorge A
Department of Chemistry and Biochemistry, Texas Tech University, Box 41061, Lubbock, Texas 79409-1061, United States.
Department of Electrical and Computer Engineering, Texas Tech University, Box 43102, Lubbock, Texas 79409, United States.
J Phys Chem A. 2024 Aug 8;128(31):6462-6473. doi: 10.1021/acs.jpca.4c03709. Epub 2024 Jul 25.
We present a complete simplest-level electron nuclear dynamics (SLEND) investigation of H + CH at collision energies E = 30, 200, and 450 eV. This reaction is relevant in astrophysics and provides a computationally feasible prototype for proton cancer therapy reactions. SLEND is a time-dependent, variational, direct, and nonadiabatic method that adopts a classical-mechanics description for the nuclei and a Thouless single-determinantal wave function for the electrons. We perform this study with our code PACE, which incorporates the One Electron Direct/Electron Repulsion Direct (OED/ERD) atomic integrals package developed by the Bartlett group. Current SLEND simulations with the 6-31G** basis set involves 2,646 trajectory calculations from 9 nonredundant, symmetry-inequivalent projectile-target orientations. For H + CH at E = 30 eV, SLEND/6-31G** simulations predict one simple scattering process, and three reactive ones: CH hydrogen substitution, CH fragmentation into two CH moieties, and CH fragmentation into CHC and H moieties, respectively. We reveal and analyze the mechanisms of these processes through computer animations; this valuable chemical information is inaccessible by experiments. The SLEND/6-31G** scattering angle functions exhibit primary and secondary rainbow scattering features that vary with the projectile-target orientations and collision energies. SLEND/6-31G** predicts 1-electron-transfer (1-ET) integral cross sections at E = 30, 200, and 450 eV in good agreement with their experimental counterparts. SLEND/6-31-G** predicts 1-ET differential cross sections (DCSs) at E = 30 eV that agree well with their experimental counterparts over all the measured scattering angles. In addition, SLEND/6-31G** predicts 0-ET DCSs at E = 30 eV that agree well with their experimental counterparts at low scattering angles, but less satisfactorily at higher ones. Remarkably, both the 0- and 1-ET DCSs from SLEND/6-31G** exhibit distinct primary rainbow scattering signatures in excellent agreement with their experimentally inferred counterparts. Furthermore, both SLEND/6-31G** and the experiment indicate that the primary rainbow scattering angles from the 0- and 1-ET DCSs are identical (an unusual fact in proton-molecule collisions). Through these rainbow scattering predictions, SLEND has also validated a procedure to extract primary rainbow angles from structureless DCSs. We analyze the obtained theoretical results in comparison with available experimental data and discuss forthcoming developments in the SLEND method.
我们展示了对H + CH在碰撞能量E = 30、200和450 eV下进行的完整的最简级电子核动力学（SLEND）研究。该反应在天体物理学中具有重要意义，并且为质子癌症治疗反应提供了一个计算上可行的原型。SLEND是一种含时、变分、直接且非绝热的方法，它对原子核采用经典力学描述，对电子采用陶勒斯单行列式波函数。我们使用我们的代码PACE进行这项研究，该代码整合了由巴特利特团队开发的单电子直接/电子排斥直接（OED/ERD）原子积分包。当前使用6 - 31G基组的SLEND模拟涉及来自9种非冗余、对称不等价的弹体 - 靶标取向的2646次轨迹计算。对于E = 30 eV时的H + CH，SLEND/6 - 31G模拟预测了一个简单散射过程和三个反应过程：CH氢取代、CH分裂成两个CH部分以及CH分裂成CHC和H部分。我们通过计算机动画揭示并分析了这些过程的机制；这些有价值的化学信息通过实验无法获取。SLEND/6 - 31G散射角函数展现出随弹体 - 靶标取向和碰撞能量变化的一级和二级彩虹散射特征。SLEND/6 - 31G预测了在E = 30、200和450 eV时的单电子转移（1 - ET）积分截面，与实验结果吻合良好。SLEND/6 - 31 - G预测了在E = 30 eV时的1 - ET微分截面（DCS），在所有测量的散射角上与实验结果都吻合得很好。此外，SLEND/6 - 31G预测了在E = 30 eV时的0 - ET DCS，在低散射角时与实验结果吻合良好，但在高散射角时不太理想。值得注意的是，SLEND/6 - 31G的0 - ET和1 - ET DCS都展现出明显的一级彩虹散射特征，与通过实验推断出的结果高度一致。此外，SLEND/6 - 31G和实验都表明，0 - ET和1 - ET DCS的一级彩虹散射角是相同的（这在质子 - 分子碰撞中是一个不寻常的事实）。通过这些彩虹散射预测，SLEND还验证了一种从无结构DCS中提取一级彩虹角的方法。我们将获得的理论结果与现有的实验数据进行比较分析，并讨论SLEND方法未来的发展。
