Fragmentation network of doubly charged methionine: Interpretation using graph theory.

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Chemical Physics

Background:

• Gas-phase molecular ions are crucial in various chemical processes.
• Understanding ion fragmentation provides insights into molecular structure and bonding.
• Previous experimental studies on methionine dication fragmentation exist.

Purpose of the Study:

• To systematically investigate the fragmentation pathways of doubly charged gas-phase methionine.
• To analyze molecular dynamics trajectories using graph theory for efficient data extraction.
• To compare theoretical findings with existing experimental results.

Main Methods:

• Self-consistent charge density functional tight-binding molecular dynamics (MD) simulations.
• Application of graph theory for analyzing MD trajectories.
• Ab initio calculations to support dissociation pathways.

Main Results:

• The doubly charged methionine dication primarily dissociates into a CO2H group and a C4NSH10 group.
• The CO2H group remains largely intact, while the C4NSH10 group further fragments.
• The fragmentation kinetics of the C4NSH10 group follows the Arrhenius law.
• Theoretical results show strong agreement with experimental data.

Conclusions:

• Molecular dynamics simulations coupled with graph theory provide effective analysis of ion fragmentation.
• The proposed dissociation mechanism for methionine dication is robust and supported by multiple computational methods.
• The study validates and extends previous experimental findings on methionine dication fragmentation.