Global accurate diabatic potential surfaces for the reaction H + Li₂

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Chemical Physics

Background:

• The Li2H system is crucial for understanding chemical reactions involving alkali metal hydrides.
• Accurate potential energy surfaces are essential for predicting reaction dynamics.

Purpose of the Study:

• To compute adiabatic potential energies for the Li2H system.
• To develop global adiabatic potential energy surfaces for the lowest two states.
• To investigate nonadiabatic processes like avoided crossings and conical intersections.

Main Methods:

• High-level ab initio calculations, specifically Multi-Configurational Self-Consistent Field (MCSCF) and Multi-Reference Configuration Interaction (MRCI) methods.
• Utilized a large atomic Natural Orbital basis set, augmented-valence quintuple-zeta (aV5Z).
• Employed a three-dimensional B-spline fitting method for global potential energy surface mapping.

Main Results:

• Calculated adiabatic potential energies for the lowest three electronic states of Li2H.
• Generated accurate global adiabatic potential energy surfaces for the two lowest states.
• Analyzed vibrational states and energies of diatomic reactants and products.
• Investigated avoided crossing areas and conical intersections to understand nonadiabatic behavior.

Conclusions:

• The study provides accurate potential energy surfaces for the Li2H system.
• Detailed analysis of nonadiabatic features facilitates further dynamic reaction studies.
• Diabatic potential energy surfaces were deduced for future nonadiabatic dynamic reaction investigations.