Non-covalent interactions

Purpose

This benchmark tests if the MLIP can reproduce interaction energies of molecular complexes driven by non-covalent interactions. Non-covalent interactions are of highest importance for the structure and function of every biological molecule. This benchmark assesses a broad range of interaction types: London dispersion, hydrogen bonds, ionic hydrogen bonds, repulsive contacts and sigma hole interactions.

Description

The benchmark leverages the mlip library for model energy inference on all structures corresponding to the distance scans of bi-molecular complexes in the dataset. The key metric is the RMSE of the interaction energy, which is the minimum of the energy well in the distance scan, relative to the energy of the dissociated complex, compared to the QM reference data. For repulsive contacts, the maximum of the energy profile is used instead.

Note that some of the molecular complexes in the benchmark dataset contain exotic elements (see dataset section). If the benchmarked MLIP cannot run an element of a molecular complex, the complex will simply be skipped.

Dataset

This benchmark uses the datasets from the NCI Atlas, with dissociation energy profiles. These datasets contain QM optimized geometries, along with CCSD(T)/CBS level interaction energies. The molecular complexes of these datasets contain typical organic small molecules, but also more exotic species and elements. Here is a summary of the datasets used in this benchmark:

NCI Atlas Datasets

Dataset Name

Type of interaction

Subsets

D442x10

London dispersion

Noble Gases, Boron, HCNO, Halogens

HB375x10

Hydrogen bonds

OH-N, OH-O, OH-C, NH-N, NH-O, …

HB300SPXx10

Hydrogen bonds extended to S, P and halogens

XH-S, XH-P, XH-Cl, XH-Br

IHB100x10

Ionic hydrogen bonds

O, N, C with cationic donors and anionic acceptors

R739x5

Repulsive contacts

HCNO, halogens, PS

SH250x10

Sigma hole interactions

P, S, Br, Cl, I

Interpretation

The RMSE of the interaction energies should be as low as possible. This metric is likely to be very different for the different interaction types and data subsets. The RMSE in interaction error should be compared per interaction type and then in a more fine-grained visualization for the data subsets to identify areas of weakness for the MLIP. Within these areas of weakness, individual dissociation energy profiles can be visually inspected to see how they compare to the reference.