PERI-CC2: A Polarizable Embedded RI-CC2 Method.

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Molecular Modeling

Background:

• Accurate simulation of large solvated molecular systems is computationally demanding.
• Studying excited state phenomena requires sophisticated correlated wave function methods.
• Polarizable embedding (PE) and resolution-of-the-identity (RI) coupled-cluster methods offer potential for improved accuracy and efficiency.

Purpose of the Study:

• To introduce and validate a novel computational approach, PERI-CC2, for studying excited state properties of large solvated systems.
• To combine the strengths of polarizable embedding (PE) and resolution-of-the-identity coupled-cluster singles and doubles (RI-CC2) methods.
• To achieve accurate correlated wave function calculations for complex molecular environments with reduced computational expense.

Main Methods:

• Development of the PERI-CC2 method by integrating the polarizable embedding (PE) approach with the resolution-of-the-identity (RI) implementation of the coupled-cluster singles and doubles (CC2) method.
• Introduction of an approximate truncated CC2 density for efficient calculation of PE contributions.
• Derivation of central equations and outlining of the implementation strategy for PERI-CC2.

Main Results:

• PERI-CC2 successfully incorporates polarization effects in solvated systems.
• The method demonstrates significantly reduced computational cost compared to previous PE-CC2 and PE-CCSD approaches.
• Validation against solvatochromic shifts of model systems and uracil in aqueous solution shows good agreement with experimental and previous theoretical results.

Conclusions:

• PERI-CC2 offers an efficient and accurate method for investigating excited state phenomena in large solvated molecular systems.
• The explicit inclusion of specific solute/solvent interactions, such as hydrogen bonds, requires careful consideration within the quantum mechanical region for reliable results.
• This new approach holds significant potential for advancing the study of complex chemical processes in solution.