Structures and Dynamics of Forsterite and Its Interstitial Water

Interstitial water of forsterite has a unique high-density structure. To investigate the structures and diffusive properties of interstitial water, we performed molecular dynamics calculations of thin water layers in forsterite in crystalline and glassy states. The results show that the density of interstitial water of forsterite in both crystalline and glassy states increases as the thickness of the water layer decreases at <3 nm. The self-diffusion coefficient of water decreases with the densification. Furthermore, it was found that the mobility of atoms in forsterite increases with the increase of the thickness of the water layer. The motion of interstitial water may propagate the motion of atoms in forsterite. The results suggest that the interstitial water of forsterite has effects to promote rearrangements of atoms in coexisting minerals and plays an important role in mineral evolutions.