State-Specific Embedding Potentials for Excitation-Energy Calculations.

Area of Science:

• Computational chemistry
• Quantum chemistry
• Theoretical chemistry

Background:

• Embedding potentials model environmental effects on molecular electronic structure.
• Significant electron density changes during excitation can necessitate state-specific potentials for accuracy.
• Existing methods may not fully capture polarization effects in responsive environments.

Purpose of the Study:

• To extend wave function in density functional theory (WF/DFT) methods for computing excitation energies.
• To incorporate state-specific density-based embedding potentials within a modified subsystem DFT approach.
• To accurately describe molecules in responsive environments, accounting for differential polarization.

Main Methods:

• Development of state-specific density-based embedding potentials.
• Modification of subsystem DFT for responsive environments.
• Evaluation of ground- and excited-state energy differences using state-independent and state-dependent potentials.
• Proposal of practical methods for constructing excited-state densities.

Main Results:

• Successful extension of WF/DFT methods to include state-specific embedding potentials.
• Demonstration of improved accuracy in calculating excitation energies for various molecules (p-nitroaniline, acrolein, methylenecyclopropene, p-nitrophenolate).
• Quantification of differential polarization effects in different solvent environments.

Conclusions:

• State-specific embedding potentials are crucial for accurate theoretical descriptions of excited states in responsive environments.
• The proposed WF/DFT approach provides a robust framework for calculating excitation energies.
• The methodology offers practical solutions for handling complex electronic structure problems in condensed phases.