The atomic and electronic structures of three Li x V 2 O 5 phases have been investigated using plane wave calculations based on density functional theory. We show that reduction of the vanadium ions occurs during lithium intercalation. At low lithium concentrations this reduction is limited to specific ions. Changes to unit cell dimensions can be predicted correctly. Calculated cell potentials are in good agreement with experiment. Initial "atomistic" calculations were successfully used to find the most stable sites for lithium in the V 2 O 5 lattice. Calculated activation energies suggest that lithium is highly mobile along the 010 direction.

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Ab initio molecular dynamics simulations predict that CaSiO3 perovskite melts at 5600 K at 136 GPa, and 6400 K at 300 GPa, significantly higher than MgSiO3 perovskite. The entropy of melting (1.8 kB per atom) is much larger than that of many silicates at ambient pressure and of simple liquids and varies little with pressure. The volume of melting decreases rapidly with increasing pressure, to 3 % at 136 GPa, producing a melting slope that diminishes rapidly with pressure. We determine the melting temperature via the ZW method, combining the Z method, for which we clarify the theoretical basis, with a waiting time analysis. The ZW method results are internally confirmed by integrating the Clausius‐Clapeyron equation, which also yields our results for the entropy and volume of melting. We find the eutectic composition on the MgSiO3‐CaSiO3 join to be xCa = 0.26 at 136 GPa and that metasilicate melt is denser than coexisting silicates.

Computer modeling techniques have been used to study the structure and energetics of H defects in Mg2SiO4 forsterite and their infrared stretching frequencies. The calculated defect binding energies indicate that OH groups will combine with cation vacancies to form neutral defect complexes. Such defect clusters are stabilized by strong hydrogen bonding. Calculated infrared stretching frequencies for OH in different environments have been determined for the first time and show two distinct groups of frequencies. The values of these frequencies, together with their directional components, are compared to experimental measurements. This comparison shows that in pure forsterite, H defects will be associated with both Si and Mg vacancies, but will not occur as isolated OH groups, in line with the results from consideration of defect energetics.