Frozen density embedding with non-integer subsystems' particle numbers.

Area of Science:

• Quantum Chemistry
• Computational Physics
• Theoretical Chemistry

Background:

• Frozen Density Embedding Theory (FDET) is a powerful method for studying complex molecular systems.
• Accurate calculations often require handling subsystems with non-integer particle numbers, a challenge for existing FDET formulations.

Purpose of the Study:

• To extend frozen density embedding theory to accommodate non-integer particle numbers in subsystems.
• To analyze the impact of non-integer particle number partitioning on embedding accuracy.
• To explore the implications for derivative discontinuity and chemical reactivity descriptors.

Main Methods:

• Development of a generalized frozen density embedding theory framework.
• Investigation of approximate embedding calculations with non-integer particle numbers.
• Analysis of the relationship between particle number partitioning schemes and embedding errors.

Main Results:

• A novel formulation of frozen density embedding theory for non-integer particle numbers is presented.
• The study identifies key factors influencing embedding errors in approximate calculations.
• The research establishes connections between the theory and fundamental chemical concepts.

Conclusions:

• The extended FDET provides a more versatile tool for electronic structure calculations.
• Understanding particle number partitioning is crucial for accurate embedding.
• The theory offers new avenues for calculating chemical reactivity descriptors and addressing the derivative discontinuity problem.