Theoretische Chemie, Fakultät für Chemie, Universität Bielefeld, Bielefeld, Germany.
J Chem Phys. 2013 Jul 7;139(1):014309. doi: 10.1063/1.4812251.
An approach to construct vibronically and spin-orbit coupled diabatic potential energy surfaces (PESs) which describe all three relevant electronic states in the entrance channels of the X(P) + CH4 →HX + CH3 reactions (with X=F((2)P), Cl((2)P), or O((3)P)) is introduced. The diabatization relies on the permutational symmetry present in the methane molecule and results in diabatic states which transform as the three p orbitals of the X atom. Spin-orbit coupling is easily and accurately included using the atomic spin-orbit coupling matrix of the isolated X atom. The method is applied to the F + CH4 system obtaining an accurate PES for the entrance channel based on ab initio multi-reference configuration interaction (MRCI) calculations. Comparing the resulting PESs with spin-orbit MRCI calculations, excellent agreement is found for the excited electronic states at all relevant geometries. The photodetachment spectrum of CH4·F(-) is investigated via full-dimensional (12D) quantum dynamics calculations on the coupled PESs using the multi-layer multi-configurational time-dependent Hartree approach. Extending previous work [J. Palma and U. Manthe, J. Chem. Phys. 137, 044306 (2012)], which was restricted to the dynamics on a single adiabatic PES, the contributions of the electronically excited states to the photodetachment spectrum are calculated and compared to experiment. Considering different experimental setups, good agreement between experiment and theory is found. Addressing questions raised in the previous work, the present dynamical calculations show that the main contribution to the second peak in the photodetachment spectrum results from electron detachment into the electronically excited states of the CH4F complex.
介绍了一种构建描述 X(P) + CH4 → HX + CH3 反应入口通道中所有三个相关电子态的振动和自旋轨道耦合非绝热势能面（PES）的方法（其中 X = F((2)P)、Cl((2)P) 或 O((3)P)）。该键合依赖于甲烷分子中的置换对称性，并导致键合态作为 X 原子的三个 p 轨道进行变换。自旋轨道耦合可以使用孤立 X 原子的原子自旋轨道耦合矩阵轻松且准确地包含在内。该方法应用于 F + CH4 体系，基于从头算多参考组态相互作用（MRCI）计算获得了入口通道的精确 PES。将得到的 PES 与自旋轨道 MRCI 计算进行比较，在所有相关几何形状下，对激发电子态都发现了极好的一致性。通过使用多层多组态时变哈特ree 方法在耦合 PES 上进行全维（12D）量子动力学计算，研究了 CH4·F(-)的光离解光谱。扩展了以前的工作[J. Palma 和 U. Manthe，J. Chem. Phys. 137, 044306 (2012)]，该工作仅限于单个绝热 PES 上的动力学，计算了电子激发态对光离解光谱的贡献，并与实验进行了比较。考虑到不同的实验设置，实验和理论之间存在良好的一致性。解决了以前工作中提出的问题，本动力学计算表明，光离解光谱中第二个峰的主要贡献来自 CH4F 络合物中电子脱离到电子激发态。
