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On the chain-melted phase of matter

On the chain-melted phase of matter
On the chain-melted phase of matter

14/04/2019

 Scientists at the ICTP, have shown matter to form both liquid and solid at the same time, recently published in the Proceedings of the National Academy of Sciences. What makes this unique is that it happens for just one element, where as the superionic state - which is similar, typically has two or more. Several elements form host-guest structures under pressure which aids this partitioning of the single element into two groups. Upon heating, the guest atoms can "melt" while existing with the crystalline solid host lattice. In this part-solid, part-liquid state, the "molten" guest atoms remain confined to 1D channels suggesting the thermodynamically forbidden 1D melting. Continuing from experimental observations of the crystal structure simulations were developed and used to fully understand what this state of matter is on the atomistic level. We develop here a classical interatomic forcefield for the element potassium using machine-learning techniques and simulate the chain-melted state with up to 20,000 atoms. We show that in the chainmelted state, guest-atom correlations are lost in three dimensions, providing the entropy necessary for its thermodynamic stability. This team composed of physicists from ICTP (Victor Naden Robinson), The University of Edinburgh, and Xi’an Jiantong University.

 

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