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Pressure-induced localisation of the hydrogen-bond network in KOH-VI
Using a combination of ab initio crystal structure prediction and neutron diffraction techniques,
we have solved the full structure of KOH-VI at 7 GPa. Rather than being orthorhombic and
proton-ordered as had previously ...
On the chain-melted phase of matter
Various single elements form incommensurate crystal structures under pressure, where a zeolite-type “host” sublattice surrounds a “guest” sublattice comprising 1D chains of atoms. On “chain melting,” diffraction peaks from ...
Stability of Hydrogen Hydrates from Second-Order Møller-Plesset Perturbation Theory
The formation of gas hydrates and clathrates critically depends on the interaction between the host water network and the guest gas species. Density functional calculations can struggle to quantitatively capture these ...
Structural and electronic properties of the alkali metal incommensurate phases
Under pressure, the alkali elements sodium, potassium, and rubidium adopt nonperiodic structures based on two incommensurate interpenetrating lattices. While all elements form the same “host” lattice, their “guest” lattices ...
High-pressure phase of brucite stable at Earth’s mantle transition zone and lower mantle conditions
We investigate the high-pressure phase diagram of the hydrous mineral brucite, Mg(OH)2, using structure search algorithms and ab initio simulations. We predict a new high-pressure phase stable at pressure and temperature ...
Changes of Fermi Surface Topology due to the Rhombohedral Distortion in SnTe
Stoichiometric SnTe is theoretically a small gap semiconductor that undergoes a ferroelectric distortion on cooling. In reality however, crystals are always nonstoichiometric and metallic; the ferroelectric transition is ...
Stabilization of ammonia-rich hydrate inside icy planets
The interior structure of the giant ice planets Uranus and Neptune, but also of newly discovered exoplanets, is loosely constrained, because limited observational data can be satisfied with various interior models. Although ...
Computational phase diagrams of noble gas hydrates under pressure
We present results from a first-principles study on the stability of noble gas-water compounds in the pressure range 0-100 kbar. Filled-ice structures based on the host water networks ice-Ih, ice-Ic, ice-II, and C0 interacting ...
High-pressure phase transitions in rubidium and caesium hydroxides
A computational investigation of the high-pressure phase sequence of the heaviest alkali hydroxides, RbOH and CsOH, shows that the phase diagram of both compounds is richer than hitherto thought. First-principles calculations ...
Novel phases in ammonia-water mixtures under pressure
While ammonia and water readily form hydrogen-bonded molecular mixtures at ambient conditions, their miscibility under pressure is not well understood, yet crucial e.g. to model the interior of icy planets. We report here ...
Rules of formation of H–C–N–O compounds at high pressure and the fates of planetary ices
The solar system’s outer planets, and many of their moons, are dominated by matter from the H–C–N–O chemical space, based on solar system abundances of hydrogen and the planetary ices H2O, CH4 , and NH3 . In the planetary ...
