Extension of frozen-density embedding theory for non-variational embedded wavefunctions

Area of Science:

• Quantum Chemistry
• Computational Physics
• Theoretical Chemistry

Background:

• Frozen-density embedding theory (FDET) is a multi-level simulation method.
• Original FDET formulation uses variational methods for embedded N_A-electron wavefunctions.

Purpose of the Study:

• To derive a general expression for total energy in FDET when embedded electrons are treated non-variationally.
• To develop an implicit density functional for total energy within this framework.

Main Methods:

• Construction of an implicit density functional for total energy.
• Derivation of a general energy expression based on linear expansion in density perturbations.

Main Results:

• A novel, exact formula for total energy in non-variational FDET is derived.
• The formula's accuracy is validated within linear density perturbation approximations.

Conclusions:

• The derived formula offers a more generalized approach to FDET calculations.
• This work extends the applicability of frozen-density embedding theory to non-variational treatments.