Polyamorphism in low temperature water:A simulation study

摘要

by performing molecular dynamics simulations we have generated several forms of high density amorphous (HDA) water (rho>=1.1 g/cm~3),either by pressurizing cubic ice or by quenchignliquidwater maintained under pressure.It is shown that the temperature of amorphization is a key variable in understanding the thermodynamic and structural properties of the resultign amrphous phase.Thus,the higher the temperature of amorphization the denser the amorphous ice recovered atlow temperature.Two limiting forms of high density are identified,a less dense on eobtained by rpessure-induced amorphization of cubic ice at low temperature which can be assigned to the HDA phase commonly investigated experimentally,and a denser form obtaine dby vitrifying the liquid under pressure whose structure is analogous to te VHDA phase rcently discovered.Upon heating,both phases transform into low density phases(LDA_I and LDA_II),respectively,with slightly different properties.In particular,it is found that th eLDA_I phase exhibits thermodynamic,structural,and dynamcial properties very close to that of hyperquenched glassy water.These findings can be udnerstood by analyzing the relative displacements of the amorphization process.this study supports the idea of a continuity of metastable amorphous phases in low temperature water.