CREST-PRP: Exploring the Quantum Potential Energy Surface of Water and Aqueous Solutions

Cuny City College, New York NY

Investigators

Abstract

The CREST Postdoctoral Research Program (CREST-PRP) provides two years of support for research, training, and mentoring experiences for individual early career scientists at active CREST Centers. The goal of the CREST-PRP awards is to increase the STEM workforce presence of individuals who are members of groups underrepresented in STEM fields. CREST-PRP awards recognize investigators with significant potential and support their research experiences to broaden their perspectives, facilitate interdisciplinary interactions, and prepare CREST-PRP scholars for positions of leadership within the scientific community. The research project, "CREST-PRP: Exploring the Quantum Potential Energy Surface of Water and Aqueous Solutions," is in direct alignment with the CREST-PRP goals. Submitted by a researcher affiliated with the CREST Center for Interface Design and Engineered Assembly of Low-dimensional Systems at the City College of New York, this project aims to extend the potential energy landscape (PEL) formalism that was originally developed to describe the behavior of classical liquids at low temperature to the case of quantum liquids. This project will generate crucial insights into understanding how nuclear quantum effects can influence the liquid to glass transition in water and aqueous solutions. The quantum potential energy landscape formalism will also provide a theoretical basis in understanding how quantum effects influence the physical and mechanical properties of water. The formalism and numerical data obtained from this project will be useful to the scientific and engineering community working on the cryopreservation of biomaterials at low temperatures, pharmaceutical and food industries interested in improving the shelf life of amorphous materials. The codes and scripts used to generate and analyze the results from this project will be made open source, user friendly and available to be used throughout the scientific community. The PEL formalism has been applied in the past to study the thermodynamics and dynamics of clusters, atoms, biomolecules, glasses and in the calculation of the equation of state of equilibrium systems. These computational studies were performed using classical molecular dynamics, where the inclusion of quantum effects are omitted. This project will extend the PEL formalism where nuclear quantum effects are explicitly included, using path integral simulations to study (i) supercooled and glassy water and (ii) aqueous solutions containing water and ions (Li+, Cl-, Na+). By using the path integral formulation of quantum mechanics, the quantum particle is mapped onto a fictitious ring- polymer mapped up of P beads, connected by harmonic springs that depend on the mass of the particle and the temperature of the system. In the path integral approach, the PEL now becomes a function of the mass of the particles and the temperature, distinct from the classical PEL, where the mass of the particle plays no role in defining the PEL. This project will seek to answer how the inclusion of quantum effects, influence the properties of the PEL (minima, curvature, and depth of the PEL), calculate an equation of state for water and aqueous solutions from the properties of the PEL, and how the inclusion of ions in water affects the glass transition in water. 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.