Bootstrap Embedding for Molecules, Materials and Electrocatalysis

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

Professor Troy Van Voorhis of Massachusetts Institute of Technology is supported by an award from the Chemical Theory, Models and Computational Methods (CTMC) program in the Division of Chemistry to study computational methods for combining calculations on small molecular fragments to make predictions about complex materials. The primary tool is a concept known as Bootstrap embedding, which allows researchers for the first time to divide a large system (say with thousands of atoms) into a number of overlapping fragments (each containing, say, ten atoms) and then stitch together those calculations to understand properties of the whole system. The resulting tools will apply to a wide range of molecules and materials and Van Voorhis will specifically use these tools to study fuel cell catalysts. Computational tools have revolutionized chemistry in recent decades and the work in this proposal will train part of the next generation of computer-savvy chemists. As part of the proposal, Van Voorhis will engage in activities aimed at improving women and under-represented minorities pursuing careers in science. In this project, we will develop new quantum mechanical fragment embedding tools that are specifically designed to be able to accurately treat both complex molecules and solids. The starting point for the work is Bootstrap Embedding (BE), a method that fundamentally solves the issue of embedding overlapping fragments. In this project, we will extend BE by while improving its accuracy and efficiency in treating large basis sets and intermolecular interactions. In a parallel effort, we will implement BE for extended systems (e.g. surfaces and solids) by incorporating periodic boundary conditions. The bootstrap conditions also naturally lead to a new form of boundary conditions (which we call “impurity boundary conditions”) that approximate the situation in which a single substrate reacts at a semi-infinite surface. As a signature application of these tools, we will study the energetics of O2 binding and subsequent proton coupled electron transfer (PCET) steps in a set of potential ORR catalysts. As the ORR half-reaction is the rate- and potential- determining step in all modern fuel cells, advances in this area have the potential for significant impacts in future fuel cell technologies. In a direct sense, the work outlined here will contribute to the training of the undergraduate, graduate and postdoctoral scholars involved in the project. In a wider sense, the project proposes a set of education, training and outreach activities aimed at increasing the participation of women and underrepresented minorities in STEM fields. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.