Dispersion-correcting potentials can significantly improve the bond dissociation enthalpies and noncovalent binding energies predicted by density-functional theory

Abstract

Dispersion-correcting potentials (DCPs) are atom-centered Gaussian functions that are applied in a manner that is similar to effective core potentials. Previous work on DCPs has focussed on their use as a simple means of improving the ability of conventional density-functional theory methods to predict the binding energies of noncovalently bonded molecular dimers. We show in this work that DCPs developed for use with the LC-ωPBE functional along with 6-31+G(2d,2p) basis sets are capable of simultaneously improving predicted noncovalent binding energies of van der Waals dimer complexes and covalent bond dissociation enthalpies in molecules. Specifically, the DCPs developed herein for the C, H, N, and O atoms provide binding energies for a set of 66 noncovalently bonded molecular dimers (the "S66" set) with a mean absolute error (MAE) of 0.21 kcal/mol, which represents an improvement of more than a factor of 10 over unadorned LC-ωPBE/6-31+G(2d,2p) and almost a factor of two improvement over LC-ωPBE/6-31+G(2d,2p) used in conjunction with the "D3" pairwise dispersion energy corrections. In addition, the DCPs reduce the MAE of calculated X-H and X-Y (X,Y = C, H, N, O) bond dissociation enthalpies for a set of 40 species from 3.2 kcal/mol obtained with unadorned LC-ωPBE/6-31+G(2d,2p) to 1.6 kcal/mol. Our findings demonstrate that broad improvements to the performance of DFT methods may be achievable through the use of DCPs.

Consistent structures and interactions by density functional theory with small atomic orbital basis sets

“…This method combination is specifically designed to work for bond dissociation enthalpies and non-covalent binding energies. 39,40 In the context of correlated wave function methods that strongly rely on error cancellation, we mention the Coulomb attenuated variants of MP2 in combination with an augmented double-zeta basis. 41 Here, the long-range attenuation of the Coulomb operator cancels most of the BSSE and, in combination with the small basis set, it reduces some intrinsic MP2 errors in the description of London dispersion interactions.…”

Dispersion Corrections Improve the Accuracy of Both Noncovalent and Covalent Interactions Energies Predicted by a Density-Functional Theory Approximation

“…This level of performance is comparable to BLYP-D3/QZVP without three-body corrections but is not competitive with other dispersion-corrected methods. In fact, even DCPs developed for use with LC-ωPBE and B3LYP perform much better that the BLYP-D3-DCP approach presented in this work, giving MAEs of 3.4 25 and 2.6 kcal/mol, 24 respectively. Performance of BLYP-D3-DCP on Bond Dissociation Enthalpies.…”

“…We previously pointed out that the omission of DCPs for these atoms is expected to have very little, if any, effect on calculated binding energies. 25 This is especially true in the case of complex 7a where the iron atom is complexed in the ferrocene moiety. Furthermore, we showed in Figure 2 that it is unnecessary to apply DCPs to the entirety of a system to benefit from their use.…”

“…The LC-ωPBE-DCP/6-31+G(2d,2p) approach gave an MAE of 1.6 kcal/mol for the same set of X−H and X−Y bonds, whereas unadorned LC-ωPBE gave an MAE of 3.2 kcal/mol. 25 Therefore, for BDEs we are able to achieve with a simple GGA functional a level of performance on par with that of a complex, range-separated functional.…”

“…An interesting aspect of DCPs is that they are able to improve the performance of DFT-based methods in predicting both noncovalent and covalent properties. 25 We recently demonstrated that the combination of DCPs with the LC-ωPBE functional results in an approach that is capable of predicting the BEs for a set of 109 noncovalently interacting dimers that constitute of the so-called S66, S22B, and HSG-A databases, vide infra, with a mean absolute error (MAE) of 0.24 kcal/mol. In comparison, the "unadorned" functional (i.e., the functional with no dispersion corrections) predicts the BEs for the 109 dimers with an MAE of 2.2 kcal/mol.…”