title: Polyamorphism of ice at low temperatures from constant-pressure simulations.
abstract: We report results of molecular dynamics simulations of amorphous ice in the pressure range 0-22.5 kbar. The high-density amorphous (HDA) ice prepared by compression of Ih ice at T=80 K is annealed to T=170 K at intermediate pressures in order to generate relaxed states. We confirm the existence of recently observed phenomena, the very high-density amorphous ice, and a continuum of HDA forms. We suggest that both phenomena have their origin in the evolution of the network topology of the annealed HDA phase with decreasing volume, resulting at low temperatures in the metastability of a range of densities.
authors.affiliation: Computational Science, Department of Chemistry and Applied Biosciences, ETH Zurich, USI Campus, Via Giuseppe Buffi 13, CH-6900 Lugano, Switzerland. martonak@phys.chem.ethz.ch
authors.forename: R
authors.initials: R
authors.lastname: Martonák
authors.forename: D
authors.initials: D
authors.lastname: Donadio
authors.forename: M
authors.initials: M
authors.lastname: Parrinello