Machine learning model for non-equilibrium structures and energies of simple molecules

Predicting molecular properties using a Machine Learning (ML) method is gaining interest among research as it offers quantum chemical accuracy at molecular mechanics speed. This prediction is performed by training an ML model using a set of reference data [mostly Density Functional Theory (DFT)] and then using it to predict properties. In this work, kernel based ML models are trained (using Bag of Bonds as well as many body tensor representation) against datasets containing non-equilibrium structures of six molecules (water, methane, ethane, propane, butane, and pentane) to predict their atomization energies and to perform a Metropolis Monte Carlo (MMC) run with simulated annealing to optimize molecular structures. The optimized structures and energies of the molecules are found to be comparable with DFT optimized structures, energies, and forces. Thus, this method offers the possibility to use a trained ML model to perform a classical simulation such as MMC without using any force field, thereby improving the accuracy of the simulation at low computational cost.