ABSTRACT
Water, despite its simple molecular structure, exhibits an extraordinary degree of complexity under supercooled and glassy conditions. Unlike most pure substances, which form a single liquid and a single glassy state when crystallization is avoided, water displays two distinct liquid states—low-density liquid (LDL) and high-density liquid (HDL)—and two corresponding amorphous forms—low-density amorphous (LDA) and high-density amorphous (HDA) ice. These forms are interconnected through a proposed liquid–liquid phase transition (LLPT), terminated by a liquid–liquid critical point (LLCP), with significant implications for cryogenic science and biomolecular preservation. This talk explores the LLPT scenario in water and its connection to the LDA–HDA transformation, which resembles a first-order phase transition. We also discuss how glasses of intermediate densities can be generated through isobaric cooling. Using molecular simulations, we demonstrate the existence of the LLCP and investigate how nuclear quantum effects (NQEs) influence its location and the thermodynamic response functions in the supercritical region. Two complementary models are employed: the coarse-grained Fermi–Jagla potential and the flexible q-TIP4P/F water model. Finally, we examine how NQEs impact both crystalline and amorphous ices, and how the potential energy landscape formalism offers insight into the identification of metastable glassy states. Applications of these phenomena to cryopreservation strategies will also be discussed.
BIOGRAPHY
Gustavo Lopez is a Professor of Chemistry at Lehman College, City University of New York (CUNY), and a member of the Chemistry and Biochemistry doctoral programs at the CUNY Graduate Center. He earned his bachelor’s degree in chemistry from the University of Puerto Rico at Humacao and his Ph.D. in chemistry from the University of Massachusetts, at Amherst. Following a postdoctoral appointment at the University of Rhode Island, he joined the Department of Chemistry at the University of Puerto Rico, at Mayaguez. In 2010, he moved to Lehman College, where he continues to teach and conduct research. His research focuses on the development and application of computational methods to investigate condensed-phase systems. Current projects include the study of supercooled and glassy water, cryopreservation of biomolecules, quantum liquids and glasses via the potential energy landscape formalism, and the behavior of nanoconfined liquids.
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