Ultrafast excited-state proton transfer dynamics using linearized pair-density functional theory.

Area of Science:

• Computational Chemistry
• Photochemistry
• Quantum Mechanics

Background:

• Simulating excited-state bond-rearrangement dynamics is challenging due to complex electronic structure changes.
• Accurate methods are needed for computationally feasible molecular dynamics of photoinduced reactions.

Purpose of the Study:

• To assess the performance of Linearized Pair-Density Functional Theory (L-PDFT) for excited-state bond-rearrangement dynamics.
• To benchmark L-PDFT using excited-state intramolecular proton transfer (ESIPT) as a stringent test case.

Main Methods:

• Performed *ab initio* molecular dynamics simulations.
• Utilized L-PDFT for accurate multistate treatment of excited-state potential energy surfaces.
• Studied 10-hydroxybenzo[h]quinoline, a known ESIPT system.

Main Results:

• L-PDFT accurately predicted ESIPT dynamics occurring within 16 fs.
• Simulations showed close agreement with experimental ultrafast fluorescence data.
• Trajectory analysis highlighted the proton's crucial role in driving ESIPT.

Conclusions:

• L-PDFT effectively describes excited-state photodynamics involving bond rearrangements.
• L-PDFT shows potential for simulating broader light-driven chemical processes.
• This method could advance studies in excited-state reactivity and photocatalysis.