FisMat2017 - Submission - View

Abstract's title: The mark of hydrogen-bond interactions in liquid methanol dynamics
Submitting author: Stefano Bellissima
Affiliation: Istituto Sistemi Complessi, CNR
Affiliation Address: Via Madonna del Piano, 10, 50019 Sesto Fiorentino FI
Country: Italy
Oral presentation/Poster (Author's request): Oral presentation
Other authors and affiliations: Miguel A. González (Institut Laue Langevin, Grenoble, France), Ubaldo Bafile (CNR - Istituto dei Sistemi Complessi, Sesto Fiorentino, Italy), Alessandro Cunsolo (National Synchrotron Light Source II - Brookhaven National Laboratory, Upton, USA), Ferdinando Formisano (CNR - Istituto Officina dei Materiali, Grenoble, France), Simone De Panfilis (Istituto Italiano di Tecnologia - Center for Life Nano Science, Roma, Italy) and Eleonora Guarini (Dip.to di Fisica e Astronomia, Università di Firenze, Italy)
Abstract

Methanol is a hydrogen-bonded liquid of enormous importance in pure and applied physics and chemistry, and is the object of innumerable studies. Yet, for a long time the fundamental aspects of its molecular dynamics have been known only to a very poor extent. However, our detailed analysis of molecular dynamics simulation results for the system at two different temperatures (300 K and 200 K), has shown that methanol exhibits a very rich dynamical behavior, which classifies it as a fluid partly similar to the most important hydrogen-bonded liquid: water. Besides the normal viscoelastic behaviour typical of a large variety of liquids, three more excitations were detected in the molecular centre-of-mass dynamic structure factor. Following the explanation proposed in the pioneering works about liquid water, the low-frequency one has been interpreted as the manifestation of a coupling between longitudinal and transverse dynamics. This fact seems to be a quite common feature of molecular liquids and, as recently shown, also of liquid metals. The other two excitations appear to be of a completely different nature: they have an optic-like character and are almost non dispersive. The analysis of simulations carried out by “switching off” the hydrogen-bond interactions allowed us to unambiguously determine the nature of such excitations and to deepen the role of hydrogen bond in liquid dynamics.