DeePKS+ABACUS as a Bridge between Expensive Quantum Mechanical Models and Machine Learning Potentials

TL;DR

This paper introduces DeePKS, a machine learning-based DFT model that efficiently approximates high-level quantum mechanical energies and forces, reducing data requirements and bridging the gap to train scalable ML potentials.

Contribution

DeePKS provides a computationally efficient ML-based correction to DFT, enabling high-accuracy QM data generation with less training data, facilitating the development of ML potentials.

Findings

DeePKS closely matches high-level QM energies and forces.

Requires significantly less training data than traditional ML potentials.

Implemented in open-source ABACUS package for periodic systems.

Abstract

Recently, the development of machine learning (ML) potentials has made it possible to perform large-scale and long-time molecular simulations with the accuracy of quantum mechanical (QM) models. However, for high-level QM methods, such as density functional theory (DFT) at the meta-GGA level and/or with exact exchange, quantum Monte Carlo, etc., generating a sufficient amount of data for training a ML potential has remained computationally challenging due to their high cost. In this work, we demonstrate that this issue can be largely alleviated with Deep Kohn-Sham (DeePKS), a ML-based DFT model. DeePKS employs a computationally efficient neural network-based functional model to construct a correction term added upon a cheap DFT model. Upon training, DeePKS offers closely-matched energies and forces compared with high-level QM method, but the number of training data required is orders of magnitude less than that required for training a reliable ML potential. As such, DeePKS can serve as a bridge between expensive QM models and ML potentials: one can generate a decent amount of high-accuracy QM data to train a DeePKS model, and then use the DeePKS model to label a much larger amount of configurations to train a ML potential. This scheme for periodic systems is implemented in a DFT package ABACUS, which is open-source and ready for use in various applications.