Design and Modeling of Molecular Solids: from Organics to Complex Hydrides

Nikolai Zarkevich, Department of Physics, Uniersity of Illinois at Urbana-Champaign

Many important materials are molecular solids. Examples include substances with molecular structure such as ice, organics, complex hydrides, etc. Their typical phonon spectra include both harmonic and non-harmonic vibrations, which cannot be addressed within the traditional harmonic approximation. Hence, a new method is needed. We develop methods for predicting enthalpy and Gibbs free energy versus temperature, and we construct pressure-temperature phase diagrams of chemical reactions by solving Gibbs equation. To exemplify these methods, we predict enthalpy of a solid-solid phase transition and melting in lithium boro-hydride, and we model destabilized reactions for the advanced high-capacity hydrogen storage.