Synopsis: Ordering in hydrogen under high pressure

Molecular dynamics studies indicate a new phase of liquid hydrogen under high pressure.
Synopsis figure
Illustration: I. Tamblyn et al., Phys. Rev. Lett. (2010).

The behavior of hydrogen under pressure affects fields ranging from condensed matter physics to astrophysics. Compressed liquid hydrogen exhibits a molecular-to-atomic transition. However, despite several experiments, the theoretical debate on the nature of this transition, in particular whether it is a continuous or discontinuous (first-order) transition, has not yet been settled.

In an article in Physical Review Letters, Isaac Tamblyn and Stanimir Bonev of Dalhousie University in Nova Scotia, Canada, employ molecular dynamics to map the phase diagram of dense hydrogen over a large range of temperatures and pressures. Their findings suggest an unreported phase in the liquid with short-ranged orientational order, resulting from a transition that they predict should occur in the liquid above 100GPa. This new phase may explain certain characteristics of the molecular-to-atomic transition, the shape of the melting line, as well as the structure of hydrogen mixtures. The authors argue that a first-order transition is likely, and the new insight provided should spur future experimental work. – Sami Mitra


Features

More Features »

Announcements

More Announcements »

Subject Areas

Fluid Dynamics

Next Synopsis

Atomic and Molecular Physics

Rotating condensates show new vortex behavior

Read More »

Related Articles

Synopsis: Turning Round Drops Square
Soft Matter

Synopsis: Turning Round Drops Square

Researchers can change the shape of a liquid drop by placing it between two stretched elastic films, allowing the drop to be used as a tiny adjustable lens. Read More »

Synopsis: Uneven Turbine Placement Improves Wind Farms
Energy Research

Synopsis: Uneven Turbine Placement Improves Wind Farms

Wind-tunnel experiments show that uneven positioning of the turbines in a wind farm can improve its power output. Read More »

Viewpoint: Cloud Drops Stick Together
Geophysics

Viewpoint: Cloud Drops Stick Together

An imaging probe on an airplane observes the clustering of water droplets in clouds, confirming a predicted effect that is correlated with rainfall. Read More »

More Articles