The pressure variable opens the door towards the synthesis of materials with unique properties, ie. superconductivity, hydrogen storage media, high-energy density and superhard materials, to name a few. Under pressure elements which would not normally combine may form stable compounds, or may mix in novel proportions. Because of this using our chemical intuition developed at 1 atm in order to predict stable phases is bound to fail. In order to enable our search for superconducting hydrogen-rich systems under pressure, we have developed XtalOpt, an open-source evolutionary algorithm for crystal structure prediction. XtalOpt has been employed to find the most stable structures of hydrides with unique stoichiometries under pressure. The electronic structure and bonding of the predicted phases has been analyzed by detailed first-principles calculations. Our focus has been on the alkali metal polyhydrides, MHn (n > 1 and M = Li, Na, K, Rb, Cs), and the alkaline earth polyhydrides MHn (n > 2 and M = Be, Mg, Ba, Sr). The results of our computational experiments, are helping us to build chemical and physical intuition for compressed solids.

Building a chemical intuition under pressure: Novel alkali metal and alkaline earth polyhydrides

248th National Meeting (2014)

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