Nonadiabatic Potential Energy Surfaces for a Molecule on a Surface as Found by Constrained Complete Active Space...

Area of Science:

• Computational Chemistry
• Surface Science
• Quantum Mechanics

Background:

• Electron-transfer processes on metal surfaces are crucial for many chemical reactions.
• Accurate theoretical models require both ground and excited state potential energy surfaces, as described by Marcus theory.
• Existing methods face challenges in simultaneously describing these surfaces for complex systems.

Purpose of the Study:

• To develop a novel computational method for generating accurate potential energy surfaces.
• To enable the study of electron-transfer mediated chemical processes on metal surfaces.
• To provide a foundation for investigating nonadiabatic dynamics near metal interfaces.

Main Methods:

• A novel dynamically weighted, state-averaged constrained CASSCF(2,2) (DW-SA-cCASSCF(2,2)) method was employed.
• This method was applied to the Anderson impurity model to generate potential energy surfaces.
• The accuracy of the ground state surface was validated using renormalization group theory for specific model problems.

Main Results:

• The DW-SA-cCASSCF(2,2) method successfully produced smooth ground and excited state potential energy surfaces.
• These surfaces effectively incorporate electronic states with charge transfer character.
• The generated ground state surface shows good agreement with established theoretical approaches for model systems.

Conclusions:

• The developed DW-SA-cCASSCF(2,2) method is a promising tool for studying electron transfer phenomena.
• It provides a pathway to accurately model chemical processes involving molecules on metal surfaces.
• Future extensions to include gradients and nonadiabatic couplings will facilitate dynamic simulations of these systems.