Embedding-theory-based simulations using experimental electron densities for the environment.

Area of Science:

• Quantum Chemistry
• Computational Materials Science

Background:

• Frozen-density embedding theory (FDET) is a multi-level computational method.
• FDET utilizes an auxiliary functional to minimize the Hohenberg-Kohn density functional.
• It allows for the treatment of different electron density components using distinct methods.

Purpose of the Study:

• To demonstrate the first application of FDET using experimental electron density data.
• To investigate the suitability of X-ray diffraction data for FDET simulations.
• To calculate excitation energies of molecular clusters using FDET.

Main Methods:

• Constrained minimization of the Hohenberg-Kohn density functional.
• Utilizing the auxiliary functional E_{v_{AB}}^{\rm FDET}[\Psi _A, \rho _B].
• Employing electron density (ρ_B(r)) reconstructed from X-ray diffraction data.

Main Results:

• FDET was successfully applied using experimentally derived electron densities.
• Excitation energies were calculated for eight hydrogen-bonded clusters.
• The study confirmed the suitability of experimental densities for FDET simulations.

Conclusions:

• Experimental electron densities are viable for use in FDET-based calculations.
• FDET provides a powerful approach for multi-level simulations involving experimental data.
• This method advances the accuracy of electronic structure calculations for complex systems.