PhD project: Packing closer than close packed

Project description

Under pressure, many elements including hydrogen, lithium, sodium, potassium and cesium adopt the close-packed face-centred cubic crystal structure - the most efficient packing of spherical objects.  Remarkably, when they melt, they get even denser.  Nobody knows why.

In this computational project, you will examine the liquid phase of high-pressure elements to determine how this occurs.  One approach is to use the "density functional theory" which allows full quantum treatment of the electrons for several hundred atoms, and correctly reproduces the effect.  Describing a liquid with only 100 atoms by careful study of the electronic quantum levels, it may be possible to discover the structure.

In parallel, it is possible to do calculations of millions of atoms.  This will require so-called two-band interatomic potentials which have been developed within the group and describe the transition of electrons from low-energy, high volume s-states to high-energy, low-volume d-states under pressure.

The project  relates to ongoing experimental work in Edinburgh's Centre for Science at Extreme Conditions. It may be held within the Condensed Matter DTC.

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