Highly efficient implementation of analytic nonadiabatic derivative couplings within the pseudospectral method.

Area of Science:

• Computational Chemistry
• Theoretical Chemistry
• Quantum Chemistry

Background:

• Nonadiabatic derivative couplings are crucial for understanding chemical dynamics.
• Accurate and efficient calculation methods are needed for complex systems.
• The Tamm-Dancoff approximation is a common approach in electronic structure theory.

Purpose of the Study:

• To report a pseudospectral implementation of nonadiabatic derivative couplings within the Tamm-Dancoff approximation.
• To evaluate the accuracy and efficiency of this novel pseudospectral method.
• To benchmark its performance against conventional spectral methods.

Main Methods:

• Pseudospectral implementation of nonadiabatic derivative couplings.
• Tamm-Dancoff approximation for electronic structure calculations.
• Benchmark calculations on fullerene systems (Cn, n up to 100).

Main Results:

• The pseudospectral method achieved mean absolute errors between 0.2% and 1.9%.
• Significant speedups were observed across various basis sets (6-31G**, 6-31++G**, cc-pVTZ).
• Speedups ranged from 10- to 75-fold compared to the conventional spectral method for fullerene calculations.

Conclusions:

• The pseudospectral method offers a highly accurate and efficient approach for calculating nonadiabatic derivative couplings.
• This method provides substantial computational advantages for large molecular systems.
• The findings pave the way for more extensive studies in chemical dynamics and spectroscopy.