Stability of alkali metal halide polymorphs as a function of pressure.

We investigated the regions of thermodynamic stability of possible modifications of the alkali metal halides as a function of pressure and type of alkali metal and halogen. Both Hartree-Fock and density functional calculations (for six different functionals) were performed. The results are in good agreement with experiment, and the trends in the computed quantities such as transition pressures and lattice parameters as a function of the ab initio method are similar to those found in earlier studies of the alkali metal sulfides.

Possible existence of alkali metal orthocarbonates at high pressure.

We investigate the possible existence of crystalline alkali metal orthocarbonates, A(4)CO(4), where A=Li, Na, K, Rb, and Cs. We study the equilibrium between the possible modifications of the orthocarbonate A(4)CO(4) and the binary mixture of the possible modifications of the alkali oxide A(2)O and those of the alkali metal carbonate A(2)CO(3) as function of pressure. In all cases, the orthocarbonate should be stable at sufficiently high pressure ranging from 22-32 GPa (Rb(4)CO(4)) to 200-220 GPa (Cs(4)CO(4)).

Computational design and prediction of interesting not-yet-synthesized structures of inorganic materials by using building unit concepts.

The computational design of new and interesting inorganic materials is still an ongoing challenge. The motivation of these efforts is to aid the often difficult task of crystal structure determination, to rationalize different but related structure types, or to help limit the domain of structures that are possible in a given system. Over the past decade, simulation methods have continuously evolved towards the prediction of new structures using minimal input information in terms of symmetry, cell parameters, or chemical composition.