A Blind Structure Prediction of Ice XIV

摘要

Many of the known ice phases exhibit a proton ordering transition,for example the transition from proton disordered hexagonal ice (Ih) to proton ordered ice XI.Most recently,two new proton ordered ice phases (XIII and XIV) have been reported relating to ice V and XII,respectively.Preparation of several ice phases is not straightforward,which explains why until recently,only one new ice phase had been discovered in the last 20 years.In particular,ordered forms of ice can be difficult to isolate within the laboratory because of kinetic barriers to molecular rotation that are important at low temperatures.Computer simulation offers an adjunct methodology in which the effects of pressure,temperature,and configuration can notionally be controlled quite precisely,to permit systematic mapping of the phase diagram.However,the verity of any simulation method hinges upon its ability to reproduce disparate state points on the phase diagram.As a challenge to theory,we recently undertook a blind test to predict the proton ordered form of ice XII termed ice XIV.