Which Electronic Structure Method to Choose in Trajectory Surface Hopping Dynamics Simulations? Azomethane as a Case...

Area of Science:

• Computational Chemistry
• Photochemistry
• Electronic Structure Theory

Background:

• Nonadiabatic dynamics simulations are vital for studying photochemical reactions.
• Accurate potential energy surfaces and couplings are essential but rarely assessed.
• The choice of electronic structure method significantly impacts simulation reliability.

Purpose of the Study:

• To benchmark various post-Hartree-Fock methods and TD-DFT functionals for nonadiabatic dynamics.
• To assess their performance in reproducing relaxation pathways and timescales.
• To identify reliable and efficient computational approaches for photochemical reaction studies.

Main Methods:

• Trajectory surface hopping dynamics simulations.
• High-accuracy XMS-CASPT2 electronic structure calculations as a benchmark.
• Assessment of CIS, ADC(2), CC2, CASSCF, and TD-DFT/TDA with PBE, PBE0, and CAM-B3LYP functionals.
• Test case: isomerization around a double bond.

Main Results:

• Multireference electronic structure methods are recommended for studying nonadiabatic decay.
• TD-DFT with TDA and hybrid functionals, along with ADC(2), are efficient alternatives.
• These alternatives can overestimate nonradiative decay yields, potentially missing deexcitation pathways.

Conclusions:

• The accuracy of electronic structure methods is critical for reliable nonadiabatic dynamics simulations.
• While multireference methods offer the highest accuracy, cost-effective alternatives exist with certain limitations.
• Careful selection of computational methods is necessary to accurately capture photochemical reaction dynamics.