Development of highly accurate approximate scheme for computing the charge transfer integral.

Area of Science:

• Computational Chemistry
• Materials Science
• Quantum Chemistry

Background:

• The charge transfer integral is vital for modeling charge transport in materials like organic semiconductors.
• Its accurate calculation depends on electronic structure theory and theoretical simplifications.

Purpose of the Study:

• To assess the performance of approximate methods for calculating the charge transfer integral.
• To compare these methods against high-level equation-of-motion coupled cluster theory.

Main Methods:

• Calculations performed on the ethylene dimer model system.
• Evaluation of energy split in dimer and fragment charge difference methods.
• Investigation of a novel Taylor expansion scheme for asymmetric fluctuations.

Main Results:

• Approximate methods show limitations for asymmetric molecular displacements compared to exact calculations.
• The Taylor expansion scheme provides a computationally efficient and accurate alternative for asymmetric fluctuations.
• The Taylor expansion method is accurate across relevant geometry fluctuations at room temperature.

Conclusions:

• The Taylor expansion method is a viable and cost-effective approach for studying charge transfer integrals.
• This method significantly reduces computational cost while maintaining high accuracy for molecular systems.