Three-State Trajectory Surface Hopping Studies of the Photodissociation Dynamics of Formaldehyde on ab Initio Potential Energy Surfaces

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• 作者：Bina Fu ; Benjamin C. Shepler ; Joel M. Bowman
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：May 25, 2011
• 年：2011
• 卷：133
• 期：20
• 页码：7957-7968
• 全文大小：1153K
• 年卷期：v.133,no.20(May 25, 2011)
• ISSN：1520-5126

文摘

Full-dimensional, three-state, surface hopping calculations of the photodissociation dynamics of formaldehyde are reported on ab initio potential energy surfaces (PESs) for electronic states S₁, T₁, and S₀. This is the first such study initiated on S₁ with ab initio-calculated spin鈥搊rbit couplings among the three states. We employ previous PESs for S₀ and T₁, and a new PES for S₁, which we describe here, as well as new spin鈥搊rbit couplings. The time-dependent electronic state populations and the branching ratio of radical products produced from S₀ and T₁ states and that of total radical products and molecular products at three total energies are calculated. Details of the surface hopping dynamics are described, and a novel pathway for isomerization on T₁ via S₀ is reported. Final translational energy distributions of H + HCO products from S₀ and T₁ are also reported as well as the translational energy distribution and final rovibrational distributions of H₂ products from the molecular channel. The present results are compared to previous trajectory calculations initiated from the global minimum of S₀. The roaming pathway leading to low rotational distribution of CO and high vibrational population of H₂ is observed in the present calculations.