A time-dependent density-functional approach to nonadiabatic electron-nucleus dynamics: formulation and photochemical...

Area of Science:

• Quantum Chemistry
• Theoretical Chemistry
• Chemical Dynamics

Background:

• Nonadiabatic dynamics are essential for understanding electron-nuclear interactions in chemical reactions.
• Quantum chemical wavefunction methods are commonly used but computationally intensive.
• Time-dependent density functional theory (TD-DFT) offers a formally exact alternative for specific electronic states.

Purpose of the Study:

• To present a TD-DFT based approach for computing nonadiabatic couplings (NACs).
• To develop full quantum wave packet and semi-classical surface hopping methods for nonadiabatic reactions.
• To investigate photochemical isomerization dynamics and dissipation effects.

Main Methods:

• Utilized a density response scheme to compute NAC vectors.
• Employed the adiabatic local density approximation (ALDA) without further approximations for electrons.
• Implemented full quantum wave packet and semi-classical surface hopping approaches.
• Incorporated Langevin dynamics to model dissipation effects.

Main Results:

• Successfully described the photochemical syn-anti isomerization dynamics of formaldimine (CH2=NH).
• Demonstrated the significant role of dissipation in nonadiabatic chemical reactions.
• Validated the TD-DFT approach for simulating complex molecular dynamics.

Conclusions:

• Accurate modeling of dissipation is critical for ab initio predictions of nonadiabatic dynamics.
• The presented TD-DFT methods provide a powerful tool for studying excited-state chemical reactions.
• Future work should focus on refining dissipation models within these theoretical frameworks.