Solvent effects in time-dependent self-consistent field methods. I. Optical response calculations.

Area of Science:

• Computational chemistry
• Theoretical chemistry
• Quantum chemistry

Background:

• Solvent effects significantly influence molecular properties and reaction pathways.
• Accurate modeling of excited states requires considering solvent interactions.
• Different theoretical approaches exist for incorporating solvent effects in quantum chemical calculations.

Purpose of the Study:

• To implement and compare three distinct excited state solvent models.
• To analyze the relationship between these models using a unified formalism.
• To investigate the impact of these models on excitation energies for molecules with varying charge transfer characteristics.

Main Methods:

• Implementation of linear response, state specific, and vertical excitation solvent models.
• Application of time-dependent self-consistent field (TD-SCF) methods.
• Calculations performed using a formalism equivalent to COSMO/CIS/AM1.
• Qualitative explanation of solvent effects using a dipole approximation.

Main Results:

• The study reveals the interrelationships between the three implemented solvent models.
• Significant differences in calculated excitation energies were observed across the models.
• The magnitude of solvent effects correlates with the excited state charge transfer character of the molecules.
• The character of the calculated excitations directly reflects the fundamental differences between the solvent models.

Conclusions:

• The choice of excited state solvent model critically affects computed excitation energies.
• The observed differences are well-explained by a dipole approximation, highlighting the importance of charge distribution.
• The study provides a consistent framework for understanding and applying excited state solvent models in computational chemistry.