Charge Transfer from Regularized Symmetry-Adapted Perturbation Theory

Area of Science:

• Quantum Chemistry
• Intermolecular Forces
• Computational Chemistry

Background:

• Charge-transfer (CT) and polarization energies are crucial in understanding molecular interactions.
• Existing methods in symmetry-adapted perturbation theory (SAPT) struggle to isolate CT energy independently and basis-set consistently.
• Current approaches lack a universally applicable definition for CT energy across various intermolecular distances.

Purpose of the Study:

• To develop a theoretically sound and basis-set independent definition for charge-transfer energy.
• To interpret charge-transfer as a quantum tunneling phenomenon.
• To provide a reliable method for determining parameters in polarization models.

Main Methods:

• Utilizing regularized symmetry-adapted perturbation theory (SAPT).
• Interpreting charge-transfer as a tunneling process.
• Developing a physically convincing definition for CT energy.

Main Results:

• A novel, basis-independent definition of charge-transfer energy is established.
• The new definition accurately captures the asymmetry of forward and backward CT.
• Secondary charge-transfer effects are successfully incorporated.
• This method allows for more confident determination of damping parameters for polarization models.

Conclusions:

• The regularized SAPT approach provides a robust framework for defining and calculating charge-transfer energy.
• This work offers a deeper physical insight into the charge-transfer process in molecular systems.
• The developed method enhances the accuracy of computational models for intermolecular interactions.