Complexity Reduction in Density Functional Theory Calculations of Large Systems: System Partitioning and Fragment Embedding

TL;DR

This paper introduces an automated methodology for simplifying large quantum systems in density functional theory by partitioning them into fragments and analyzing inter-fragment interactions, facilitating better understanding and design.

Contribution

It presents a novel, automated system partitioning and interaction quantification method that requires no prior information, applicable to diverse large-scale systems in DFT calculations.

Findings

Enables systematic complexity reduction of large systems

Derives new system descriptors for analysis

Supports design of QM/MM partitioning schemes

Abstract

With the development of low order scaling methods for performing Kohn-Sham Density Functional Theory, it is now possible to perform fully quantum mechanical calculations of systems containing tens of thousands of atoms. However, with an increase in the size of system treated comes an increase in complexity, making it challenging to analyze such large systems and determine the cause of emergent properties. To address this issue, in this paper we present a systematic complexity reduction methodology which can break down large systems into their constituent fragments, and quantify inter-fragment interactions. The methodology proposed here requires no a priori information or user interaction, allowing a single workflow to be automatically applied to any system of interest. We apply this approach to a variety of different systems, and show how it allows for the derivation of new system descriptors, the design of QM/MM partitioning schemes, and the novel application of graph metrics to molecules and materials.