Time-Dependent Electronic Populations in Fragment-Based Time-Dependent Density Functional Theory.

Area of Science:

• Quantum Chemistry
• Computational Physics
• Theoretical Chemistry

Background:

• Molecular fragmentation is a fundamental concept in chemistry and physics.
• Fragmentation schemes enable efficient quantum chemistry algorithms for bond dynamics.
• Previous work established foundational methods for electronic dynamics.

Purpose of the Study:

• To present a formally exact time-dependent density functional theory for molecular fragments.
• To extend existing formalisms for electronic dynamics of subunits with variable electron numbers.
• To introduce a stable density-inversion method for time-dependent and ground-state theories.

Main Methods:

• Development of a formally exact time-dependent density functional theory (TDDFT) for molecular fragments.
• Extension of TDDFT to handle fragments with a variable number of electrons.
• Introduction of a stable density-inversion technique.

Main Results:

• A novel TDDFT formalism for the electronic dynamics of molecular fragments.
• The formalism accurately describes chemical bond formation and breaking.
• A stable density-inversion method applicable to various TDDFT and ground-state DFT extensions.

Conclusions:

• The new TDDFT formalism provides an exact and efficient method for studying molecular fragment electronic dynamics.
• The density-inversion method enhances the stability and applicability of DFT.
• This work advances computational methods for understanding chemical reactivity and molecular behavior.