Extending Atom-Atom Polarizabilities to Frequency-Dependent Coupled Cluster and MCSCF Response.

Area of Science:

• * Quantum Chemistry
• * Computational Chemistry
• * Molecular Modeling

Background:

• * Distributed atom-atom polarizabilities are crucial for understanding molecular response properties.
• * Existing methods have limitations in handling complex wave functions and dynamic perturbations.

Purpose of the Study:

• * To extend the minimal basis iterative Stockholder partitioning framework for calculating distributed atom-atom polarizabilities.
• * To incorporate coupled cluster (CC2, CCSD, CC3) and multiconfigurational self-consistent field (MCSCF) wave functions.
• * To investigate frequency-dependent polarizabilities and benchmark bond capacity.

Main Methods:

• * Extension of the minimal basis iterative Stockholder partitioning framework.
• * Application to CC2, CCSD, CC3, and MCSCF wave functions.
• * Calculation of static and frequency-dependent polarizabilities, including bond capacity.

Main Results:

• * Good agreement between DFT functionals and CC3 for equilibrium geometries and minor geometric changes.
• * Significant method-dependent deviations observed for S_N2 reaction pathways.
• * Rank-0 contribution found to dominate molecular dipole polarizability during bond breaking.
• * Non-nuclear sites were ineffective for describing out-of-plane polarizability.

Conclusions:

• * The extended methodology provides a robust framework for calculating polarizabilities across various quantum chemical methods.
• * Method dependence is significant for reaction pathways and dynamic properties.
• * Rank-0 contributions are vital for understanding molecular polarizability, especially during bond breaking.