title: How many amorphous ices are there?
abstract: Many acronyms are used in the literature for describing different kinds of amorphous ice, mainly because many different preparation routes and many different sample histories need to be distinguished. We here introduce these amorphous ices and discuss the question of how many of these forms are of relevance in the context of polyamorphism. We employ the criterion of reversible transitions between amorphous "states" in finite intervals of pressure and temperature to discriminate between independent metastable amorphous "states" and between "substates" of the same amorphous "state". We argue that the experimental evidence suggests we should consider there to be three polyamorphic "states" of ice, namely low-(LDA), high-(HDA) and very high-density amorphous ice (VHDA). In addition to the realization of reversible transitions between them, they differ in terms of their properties, e.g., compressibility, or number of "interstitial" water molecules. Thus they cannot be regarded as structurally relaxed variants of each other and so we suggest considering them as three distinct megabasins in an energy landscape visualization.
authors: Institute of Physical Chemistry University of Innsbruck, Innrain 52a, A-6020 Innsbruck, Austria. thomas.loerting@uibk.ac.at
authors: Thomas
authors: T
authors: Loerting
authors: Katrin
authors: K
authors: Winkel
authors: Markus
authors: M
authors: Seidl
authors: Marion
authors: M
authors: Bauer
authors: Christian
authors: C
authors: Mitterdorfer
authors: Philip H
authors: PH
authors: Handle
authors: Christoph G
authors: CG
authors: Salzmann
authors: Erwin
authors: E
authors: Mayer
authors: John L
authors: JL
authors: Finney
authors: Daniel T
authors: DT
authors: Bowron
mesh_terms: D007053:Ice; D011312:Pressure; D013696:Temperature
chemical_list: D007053:Ice