Glycine in an electronically excited state: ab initio electronic structure and dynamical calculations

Area of Science:

• Photochemistry
• Quantum Chemistry
• Molecular Dynamics

Background:

• Glycine is the simplest amino acid.
• Understanding its excited-state dynamics is crucial for chemical and biological processes.

Purpose of the Study:

• To investigate the photochemical pathways of glycine after optical excitation.
• To map the potential energy surfaces (PES) of glycine's ground and excited states.
• To determine the influence of conformation on glycine's photochemistry.

Main Methods:

• High-level electronic structure calculations.
• Potential Energy Surface (PES) mapping.
• Ab Initio Multiple Spawning (AIMS) dynamical calculations.

Main Results:

• Glycine's photochemistry is a hybrid of amine and carboxylic acid behaviors.
• Ultrafast decay is linked to the amino group; slower channels involve the carboxylic group.
• Conformationally dependent dynamics were found to be of minor relevance.

Conclusions:

• Glycine exhibits dual photochemical behavior based on its functional groups.
• The timescale of decay is dictated by the specific functional group involved.
• Conformational effects on glycine photochemistry are limited.