Synopsis

Ordering in hydrogen under high pressure

Physics 3, s18
Molecular dynamics studies indicate a new phase of liquid hydrogen under high pressure.
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


Subject Areas

Fluid Dynamics

Related Articles

How a Swirling Tail Helps Microbes Swim 
Biological Physics

How a Swirling Tail Helps Microbes Swim 

A microswimmer that rotates its body and tail in opposite directions can propel itself in elastic, non-Newtonian fluids. Read More »

Cloaking and Shielding Objects in a Fluid Flow
Fluid Dynamics

Cloaking and Shielding Objects in a Fluid Flow

By injecting momentum into the fluid around an object, researchers can freely switch between obscuring the object’s presence and canceling hydrodynamic forces on it. Read More »

Cubes Keep Their Distance
Fluid Dynamics

Cubes Keep Their Distance

Cubes suspended in a liquid are less likely than spheres to form clusters and fall out of solution. Read More »

More Articles