Going beyond the three-state ensemble model: the electronic chemical potential and Fukui function for the general...

Area of Science:

• Quantum Chemistry
• Theoretical Chemistry
• Computational Chemistry

Background:

• Chemical potential and Fukui function are key descriptors of chemical reactivity.
• Traditional methods often simplify electronic state ensembles, potentially limiting accuracy under varying conditions.

Purpose of the Study:

• To derive general analytical equations for chemical potential and Fukui function.
• To assess the validity of simplified ensemble models (e.g., three ground states) across various temperatures.
• To investigate the influence of excited states on chemical reactivity, especially under extreme conditions.

Main Methods:

• Utilized the grand canonical ensemble framework.
• Derived general analytical expressions for chemical potential and Fukui function.
• Applied the methodology to the copper atom, considering various ensemble models.

Main Results:

• Established that three consecutive ground states offer a satisfactory description of chemical potential and Fukui function at chemically relevant temperatures.
• Identified specific scenarios, such as quasi-degenerate states or low-lying excited states, requiring cautious interpretation.
• Demonstrated that low-lying excited states of copper species significantly influence chemical reactivity even at moderate temperatures (~2000 K).

Conclusions:

• The derived general approach provides a robust method for studying chemical reactivity.
• The findings highlight the importance of considering excited states for accurate reactivity predictions, particularly under extreme conditions.
• This work offers a novel pathway for exploring chemical species' behavior under demanding environmental parameters.