The water-benzene interaction: insight from electronic structure theories

Area of Science:

• Computational chemistry
• Quantum chemistry
• Theoretical chemistry

Background:

• Accurate description of weak noncovalent interactions (van der Waals, hydrogen bonding) is crucial but challenging for electronic structure theories.
• These interactions are fundamental to many natural phenomena, including molecular recognition and material properties.

Purpose of the Study:

• To evaluate the performance of various electronic structure theories in describing the binding energy curve of a water-benzene complex.
• To compare the accuracy of methods like Hartree-Fock, Møller-Plesset perturbation theory, coupled cluster, density functional theory (DFT), and quantum Monte Carlo (QMC).

Main Methods:

• Hartree-Fock (HF) theory
• Second-order Møller-Plesset perturbation theory (MP2)
• Coupled Cluster (CC) methods, including CCSD(T)
• Density Functional Theory (DFT) with various exchange-correlation functionals
• DFT with empirical van der Waals (vdW) corrections
• Quantum Monte Carlo (QMC) methods

Main Results:

• Quantum Monte Carlo (QMC) and coupled cluster with single, double, and perturbative triple excitations [CCSD(T)] demonstrate strong agreement for the water-benzene binding energy curve over most distances.
• Deviations between QMC and CCSD(T) are observed at short distances, on the order of 20 meV.
• The study provides insights into the reliability of different computational methods for modeling noncovalent interactions.

Conclusions:

• QMC and CCSD(T) are highly reliable methods for describing weak noncovalent interactions, particularly van der Waals forces.
• These findings validate QMC as a robust tool for studying noncovalent interactions, an area with fewer existing QMC reports.
• The results aid in selecting appropriate computational methods for accurate modeling of molecular systems dominated by noncovalent forces.