Local-Field Effects in Linear Response Properties within a Polarizable Frozen Density Embedding Method.

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Molecular Modeling

Background:

• Accurate calculation of molecular polarizabilities is crucial for understanding chemical interactions.
• Existing methods for coupled subsystems often involve computationally expensive procedures.
• Modeling the polarization of frozen environments requires robust atomic polarizability models.

Purpose of the Study:

• To develop an efficient polarizable frozen density embedding (FDE) method for calculating polarizabilities of coupled subsystems.
• To introduce a system-independent atomic polarizability model for frozen environments.
• To validate the method's accuracy against supermolecular calculations.

Main Methods:

• Developed a polarizable frozen density embedding method (FDE-pol) combining FDE with an explicit polarization model.
• Introduced a Hirshfeld partition-based, density-dependent method for atomic polarizabilities.
• Enforced external orthogonality between subsystems to avoid approximate potentials.
• Utilized damped response theory to describe frequency-dependent polarizabilities.

Main Results:

• FDE-pol accurately calculates both uncoupled and coupled polarizabilities of molecular complexes.
• The Hirshfeld-based method predicts molecular polarizabilities near the basis set limit.
• A single scaling parameter improves agreement with reference polarizability data.
• Including local field effects is essential for coupled frequency-dependent polarizability.

Conclusions:

• The FDE-pol method provides an accurate and efficient way to compute polarizabilities for coupled subsystems.
• Accurate atomic polarizability models are vital for describing the response properties of interacting molecules.
• The developed method highlights the importance of local field effects in molecular response theory.