Calculation of intermolecular interactions in the benzene dimer using coupled-cluster and local electron correlation...

Area of Science:

• Computational chemistry
• Quantum chemistry
• Molecular modeling

Background:

• Accurate calculation of non-covalent interactions is crucial for understanding molecular systems.
• Benzene dimer serves as a model system for pi-stacked interactions.
• Traditional Møller–Plesset perturbation theory methods can overestimate dispersion interactions.

Purpose of the Study:

• To compute potential energy curves for different benzene dimer structures.
• To evaluate the performance of density-fitted local second-order Møller–Plesset perturbation theory (DF-LMP2) and its spin-component scaled variant (DF-SCS-LMP2).
• To assess the accuracy and efficiency of DF-SCS-LMP2 for describing dispersion interactions.

Main Methods:

• Density-fitted local second-order Møller–Plesset perturbation theory (DF-LMP2).
• Spin-component scaled variant of DF-LMP2 (DF-SCS-LMP2).
• Calculation of potential energy curves for parallel-displaced, T-shaped, and sandwich benzene dimer structures.

Main Results:

• Standard DF-LMP2 overestimates dispersion interactions, similar to canonical MP2.
• DF-SCS-LMP2 yields interaction energies in excellent agreement with high-level literature data.
• DF-SCS-LMP2 dissociation energies align well with complete basis set estimates.
• Basis set superposition errors are negligible with LMP2, eliminating the need for counterpoise corrections.

Conclusions:

• DF-SCS-LMP2 is a computationally inexpensive and accurate method for calculating interaction energies.
• This method shows promise for the investigation of larger pi-stacked systems, including DNA fragments.
• The study highlights the importance of spin-component scaling in improving MP2-type calculations for dispersion-dominated interactions.