N-state adiabatic-to-diabatic transformation angle: theory and application

Area of Science:

• Quantum Chemistry
• Theoretical Chemistry
• Computational Chemistry

Background:

• Diabatization is crucial for understanding non-adiabatic dynamics in chemical systems.
• Existing diabatization methods can be complex and computationally intensive.
• Accurate diabatization is essential for simulating chemical reactions and energy transfer processes.

Purpose of the Study:

• To introduce a novel, reliable, and user-friendly diabatization procedure.
• To develop a method that accounts for key physical parameters: Hilbert subspace size (N) and total energy (E).
• To specifically address the case where N is arbitrary and the number of open states (p) is two.

Main Methods:

• The proposed procedure incorporates the dimension of the adiabatic-to-diabatic transformation matrix (N).
• It considers the total energy (E) to determine the number of energetically accessible (open) states (p).
• Focuses on the theoretical framework for arbitrary N and p=2, validated by numerical examples.

Main Results:

• The new diabatization procedure is shown to be both reliable and relatively easy to implement.
• Numerical examples from three- to five-state ab initio calculations for the H + H2 system demonstrate the method's efficacy.
• The procedure successfully handles systems where N is arbitrary and p=2.

Conclusions:

• The developed diabatization method offers a practical approach for theoretical and computational chemists.
• It provides accurate results for systems with a small number of open states, as exemplified by the H + H2 reaction.
• This work contributes to more efficient and accessible modeling of chemical dynamics.