How Dimensionality, Topology, and Void Space Influence the vander Waals Scaling Landscape across the Nanoscale

Robert A. DiStasio Jr. 
Assistant Professor
Cornell University

Recent experiments on non-covalent interactions at the nanoscale have challenged the basic assumptions of commonly used particle- or fragment-based models for describing van der Waals(vdW) or dispersion forces. In the first part of this talk, we demonstrate that a qualitatively correct description of the vdW interactions between polarizable nanostructures over a wide range of finite distances can only be attained by accounting for the wavelike nature of charge density fluctuations. By considering a diverse set of materials and biological systems with markedly different dimensionalities, topologies, and polarizabilities, we find a visible enhancement in the non-locality of the charge density response in the range of 10 to 20 nanometers. These collective wavelike fluctuations are responsible for the emergence of non-trivial modifications of the power laws that govern non-covalent interactions at the nanoscale.

Despite the importance of porous two-dimensional (2D) molecules and materials in advanced technological applications, the question of how the void space in these systems affects the vdW scaling landscape has been largely unanswered. In the second part of this talk, we present a series of analytical and numerical models demonstrating that the mere presence of a pore leads to markedly different vdW scaling across non-asymptotic distances, with certain relative pore sizes yielding effective power laws ranging from simple monotonic decay to the formation of minima, extended plateaus, and even maxima. These models are in remarkable agreement with first-principles approaches for the 2D building blocks of covalent organic frameworks (COFs), and reveal that COF macrocycle dimers and periodic bilayers exhibit unique vdW scaling behavior that is quite distinct from their non-porous analogs. These findings extend across a range of distances relevant to the nanoscale, and represent a hitherto unexplored avenue towards governing the self-assembly of complex nanostructures from porous 2D molecules and materials.

Speaker Bio
Robert A. DiStasio Jr. is currently an Assistant Professor of Chemistry and Chemical Biology at Cornell University. His research group focuses on development, implementation, and application of novel methodologies that extend the frontiers of Electronic Structure Theory in complex condense-phase environments. Born and raised in Brooklyn, NY, DiStasio was the first member of his family to attend college. He graduated summa cum laude from Portland State University in 2003 with degrees in Chemistry and Biology while working with Carl C. Wamser and the late George S. Hammond. DiStasio then relocated to the Bay Area to begin graduate studies at UC Berkeley with Martin Head-Gordon. In 2009, he received a Ph.D. in Theoretical Chemistry for his work on local and canonical approximations in Møller-Plesset perturbation theory with applications to dispersion interactions. This was followed by postdoctoral research at Princeton, where he worked with Roberto Car, Salvatore Torquato, and Frank H. Stillinger, as well as Alexandre Tkatchenko and Matthias Scheffler (at the Fritz Haber Institute of the Max Planck Society in Berlin).

DiStasio has given more than 75 seminars and colloquia worldwide, published more than 60 articles in peer-reviewed academic journals, and is an active contributor to the Q-Chem and Quantum ESPRESSO software packages. He is the proud recipient of the Faculty Early Career Development (CAREER) Award from the National Science Foundation (NSF) andthe 2020 American Chemical Society (ACS) Open Eye Outstanding Junior Faculty Award in Computational Chemistry. In 2020, DiStasio was also awarded a Sloan Research Fellowship from the Alfred P. Sloan Foundation.