Chemical Physics Graduate Student Publishes in PNAS

Graduate student Thomas J. Longo (IPST Chemical Physics) with Mikhail Anisimov (IPST/Chemical and Biomolecular Engineering) et al. published the article “Formation of dissipative structures in microscopic models of mixtures with species interconversion” in PNAS, Vol. 120, No. 1, December 29, 2022.

The separation of substances into different phases is ubiquitous in nature and important scientifically and technologically. This phenomenon may become drastically different if the species involved, whether molecules or supramolecular assemblies, interconvert. In the presence of an external force large enough to overcome energetic differences between the interconvertible species (forced interconversion), the two alternative species will be present in equal amounts, and the striking phenomenon of steady-state, restricted phase separation into mesoscales is observed. Such microphase separation is one of the simplest examples of dissipative structures in condensed matter. In this work, the team investigated the formation of such mesoscale steady-state structures through Monte Carlo and molecular dynamics simulations of three physically distinct microscopic models of binary mixtures that exhibit both equilibrium (natural) interconversion and a nonequilibrium source of forced interconversion.

The team shows how a nonequilibrium bicontinuous microemulsion or a spatially modulated state may be generated depending on the interplay between diffusion, natural interconversion, and forced interconversion.

A 3rd year Ph.D. student, Longo has produced 7 significant papers, including a Chapter of a book dedicated to the memory of Michael Fisher. He will defend his Dissertation on March 6, 2023.