Explicit correlation and intermolecular interactions: investigating carbon dioxide complexes with the CCSD(T)-F12...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Molecular Interactions

Background:

• Accurate calculation of interaction energies is crucial for understanding molecular complexes.
• Traditional computational methods may struggle to achieve the desired accuracy for weakly bound systems.
• Explicitly correlated methods offer a potential pathway to improved accuracy.

Purpose of the Study:

• To evaluate the performance of newly developed explicitly correlated coupled cluster singles doubles and perturbative triples [CCSD(T)]-F12 methods.
• To determine the lowest energy structures and interaction energies for various CO2-dimer complexes.
• To compare the accuracy of CCSD(T)-F12 with conventional coupled cluster methods.

Main Methods:

• Utilized explicitly correlated coupled cluster singles doubles and perturbative triples [CCSD(T)]-F12 methods.
• Employed associated VXZ-F12 (where X = D,T,Q) basis sets for calculations.
• Optimized lowest energy structures and calculated interaction energies for dimers including CO2-Ar, CO2-N2, CO2-CO, CO2-H2O, and CO2-NH3.

Main Results:

• CCSD(T)-F12 methods yield results significantly closer to the complete basis set limit compared to conventional CCSD(T).
• The computational cost increase for CCSD(T)-F12 is modest relative to the substantial gain in accuracy.
• Accurate equilibrium geometries and interaction energies were determined for the studied dimers.

Conclusions:

• CCSD(T)-F12 methods, combined with VXZ-F12 basis sets, are highly recommended for accurate studies of weakly bound electron donor-acceptor complexes.
• These methods offer a favorable balance between computational cost and accuracy.
• The study validates the utility of explicitly correlated coupled cluster methods in computational chemistry.