Coupled-cluster frozen-density embedding using resolution of the identity methods

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Solvatochromic shifts are crucial for understanding molecular properties in different environments.
• Accurate calculations require efficient methods to handle large, complex systems.

Purpose of the Study:

• To combine Frozen-Density Embedding (FDE) with Resolution of the Identity (RI) coupled-cluster methods (RI-CC2).
• To determine solvatochromic shifts for the lowest excitation energy of acetone and pyridazine in various solutions.
• To assess the efficiency and accuracy of the combined FDE-RI-CC2 approach for condensed-phase simulations.

Main Methods:

• Frozen-Density Embedding (FDE) combined with RI-Hartree-Fock and RI-CC2.
• Calculation of solvatochromic shifts for acetone and pyridazine.
• Simulation of solvated systems with 100-300 molecules (approx. 2.5 nm diameter).
• Utilized larger basis sets and diffuse functions for enhanced accuracy.

Main Results:

• The FDE-RI-CC2 method significantly increases computational efficiency.
• Enabled calculations of numerous snapshots for condensed-phase systems.
• Achieved maximum errors of up to 0.2 eV in solvatochromic shifts.
• Results are comparable to other approximated methods in the literature.

Conclusions:

• The FDE-RI-CC2 approach is an efficient and accurate method for studying solvatochromic shifts.
• This method facilitates the simulation of larger, more realistic molecular environments.
• The findings support the use of FDE-RI-CC2 for future condensed-phase quantum chemistry studies.