Linked Product Approximation to the Global Electronic Overlap Matrix.

Area of Science:

• Quantum chemistry
• Computational physics
• Chemical dynamics

Background:

• The Born-Oppenheimer approximation is a cornerstone of molecular quantum mechanics.
• Nonadiabatic conical intersections are crucial for understanding many chemical processes.
• Calculating the global many-electron wave function overlap matrix is computationally intensive.

Purpose of the Study:

• To develop a computationally efficient method for constructing the electronic overlap matrix.
• To reduce the computational cost associated with modeling nonadiabatic conical intersection dynamics.
• To assess the accuracy of an approximate overlap matrix for wave packet dynamics.

Main Methods:

• Developed an approximation for the electronic overlap matrix using nearest-neighbor overlap matrices (links).
• Employed the discrete variable local diabatic representation for numerically exact simulations.
• Utilized a proton-coupled electron transfer model for validation.

Main Results:

• The approximation significantly reduces computational effort by limiting electronic structure calculations to nearest-neighbor overlaps.
• The approximate overlap matrix showed noticeable differences from exact calculations.
• Conical intersection dynamics simulated with the approximate matrix closely matched those using the exact matrix.

Conclusions:

• The proposed approximation offers a computationally feasible approach to constructing electronic overlap matrices.
• This method enables accurate modeling of nonadiabatic conical intersection dynamics with reduced computational cost.
• The approximation is effective for simulating complex chemical dynamics, such as proton-coupled electron transfer.