Open-Shell Variant of the London Dispersion-Corrected Hartree–Fock Method (HFLD) for the Quantification and Analysis of Noncovalent Interaction Energies

Abstract

The London dispersion (LD)-corrected Hartree–Fock (HF) method (HFLD) is an ab initio approach for the quantification and analysis of noncovalent interactions (NCIs) in large systems that is based on the domain-based local pair natural orbital coupled-cluster (DLPNO-CC) theory. In the original HFLD paper, we discussed the implementation, accuracy, and efficiency of its closed-shell variant. Herein, an extension of this method to open-shell molecular systems is presented. Its accuracy is tested on challenging benchmark sets for NCIs, using CCSD(T) energies at the estimated complete basis set limit as reference. The HFLD scheme was found to be as accurate as the best-performing dispersion-corrected exchange-correlation functionals, while being nonempirical and equally efficient. In addition, it can be combined with the well-established local energy decomposition (LED) for the analysis of NCIs, thus yielding additional physical insights.

Exploring the Accuracy Limits of PNO-Based Local Coupled-Cluster Calculations for Transition-Metal Complexes

“… 21 , 22 In particular, the two-point CPS(6/7) extrapolation scheme 21 , 22 allows DLPNO-CCSD(T) relative energy calculations with sub-kJ/mol accuracy with respect to canonical CCSD(T). 21 − 24 It is worth mentioning here that other extrapolation approaches have been suggested for local correlation methods with varying degree of accuracy. 14 , 25 − 28 …”

“…However, for systems with a complex electronic structure, tighter T CutPNO values might be necessary, which necessarily reduces the efficiency of the methodology. As an alternative to tightening the T CutPNO threshold for approaching the complete PNO space (CPS) limit with a given atomic orbital basis set, extrapolation schemes that exploit the smooth dependence of the correlation energy on the T CutPNO parameter can be used. , In particular, the two-point CPS­(6/7) extrapolation scheme , allows DLPNO-CCSD­(T) relative energy calculations with sub-kJ/mol accuracy with respect to canonical CCSD­(T). − It is worth mentioning here that other extrapolation approaches have been suggested for local correlation methods with varying degree of accuracy. ,− …”

Exploring the Limits of Intramolecular London Dispersion Stabilization with Bulky Dispersion Energy Donors in Alkane Solution

“…Accurate quantum mechanical calculations at the HFLD* level , were carried out to estimate the magnitude of intermolecular LD interactions in the solid state. With a cluster model of 11 di-adamantyl COT monomers extracted from the experimental crystal structure (Figure b), we found that the LD energy between the central monomer and its neighbors amounts to −68.2 kcal mol –1 .…”

Dimerization of confined Brønsted acids in enantioselective organocatalytic reactions

“…2 shows the most stable conformers found from the sampling procedure for all the catalysts studied in this work. The corresponding dispersion interaction density (DID) 83,84 plots at the HFLD/Silver level 85 are also shown and provide a spatial analysis of the role played by London dispersion forces acting between the monomers.…”