An assessment of the random-phase approximation functional and characteristics analysis for noncovalent cation–π interactions

Abstract

The binding energy is of great importance in understanding the formation and stability of noncovalent interactions. However, the determination of the binding energy with high precision and efficiency in medium- and long-range noncovalent interactions is still challenging for quantum chemistry. Here, we assess the performance of random-phase approximation (RPA), a fully non-local fifth-rung of the Jacob ladder functional, in determining the binding energy of cation-π systems (cation = Li, Na, Be, Mg, Al, and NH; π = CH), which, to the best of our knowledge, has not been investigated. Using experimental results as the benchmark, we systematically compared the RPA method to the other ab initio methods (DFT/B3LYP, MP2, CCSD(T), and QCISD(T)) both in calculation accuracy and efficiency. From the perspective of accuracy, RPA is the best among these approaches, followed by the CCSD(T) and QCISD(T) methods. DFT/B3LYP and MP2 provide the worst accuracy. In addition, the computational efficiency of RPA is much faster than that of CCSD(T) and QCISD(T). We believe that RPA is a robust method for the precise description of medium- and long-range noncovalent interactions and is capable of providing benchmarking data. The interaction strength and interaction nature of cation-π systems are further analyzed by atoms in molecules (AIM) and the color-mapped reduced density gradient (RDG) isosurface, which are consistent with the characteristics of a typical cation-π interaction.

Description of noncovalent interactions involving π‐system with high precision: An assessment of RPA, MP2, and DFT‐D methods

“…In our previous study, the performance of standard RPA for electrostatic‐dominated cation–π complexes has been confirmed . However, the RPA test of S22 molecular set indicates that RPA not always the best one.…”

“…For cation–benzene and anion–hexafluorobenzene systems, the optimized geometries are based on B3LYP/6‐311++G** and MP2/6‐31++G** levels, respectively. The geometries of the benzene dimers are taken from Reference .…”

“…Nowadays, Møller–Plesset perturbation theory (MP2), coupled‐cluster singles, doubles with perturbative triples (CCSD(T)) and density functional theory (DFT) are widely used to study the interactions of π‐system . CCSD(T) as the “gold standard,” its application can be expanded to the medium‐sized molecules by linear‐scaling CCSD(T) method .…”

“…Noncovalent interactions involving π‐system, such as cation–π, anion–π, π–π stacking, and so forth, play important role in various fields . For example, π–π interaction plays a key role in protein folding, stabilizing the double helical structure of DNA, the packing of aromatic molecules in crystal, and drug–receptor interactions.…”

Assessment of Computational Methods for Calculating Accurate Non-covalent Interaction Energies in 1,2,3,5-Dithiadiazolyl Radicals

“…Establishing the strengths of these interactions and their hierarchical nature is central to future work in materials design. While information on sublimation energies could give some insight into the sum of all intermolecular forces, measurements of individual intermolecular interactions are a significant challenge and best undertaken computationally. − Early approaches to understanding the hierarchy of intermolecular forces in DTDA radicals employed a simple atom–atom potential model based on a Lennard-Jones potential for dispersion, coupled with atom-based partial charges for electrostatics derived from molecular electrostatic potential surfaces . These replicated the structural features, but the total energies were potentially unreliable since the molecular electrostatic potential (MEP)-derived charges were extracted from semi-empirical methods and additional intermolecular forces, such as charge-transfer interactions, were entirely neglected.…”