A Constrained CASSCF(2,2) Approach to Study Electron Transfer between a Molecule and Metal Cluster

Area of Science:

• Computational chemistry
• Physical chemistry
• Quantum chemistry

Background:

• Electron transfer is fundamental to chemical reactions.
• Understanding homogeneous vs. heterogeneous electron transfer is crucial.
• Computational modeling aids in studying complex chemical systems.

Purpose of the Study:

• To investigate thermal electron transfer between a chlorine ion and lithium clusters.
• To analyze the influence of cluster size and geometry on electron transfer dynamics.
• To establish a computational foundation for studying heterogeneous electron transfer.

Main Methods:

• Constrained Configuration Interaction Self-Consistent Field (CASSCF) calculations.
• Utilized a CASSCF(2,2) level of theory.
• Varied lithium cluster size from 1 to 17 atoms.

Main Results:

• Demonstrated sensitive dependence of the ground state-charge transfer crossing point geometry on cluster size.
• Showcased how diabatic coupling strength is affected by the number of lithium ions.
• Highlighted the role of donor-acceptor relative positioning in electron transfer.
• Identified key factors influencing the transition from homogeneous to heterogeneous electron transfer.

Conclusions:

• The size and geometry of lithium clusters critically influence electron transfer with chlorine ions.
• Constrained CASSCF calculations provide a scalable method for studying larger systems.
• This research serves as a stepping stone towards modeling electrochemical phenomena computationally.