Structure, thermodynamic and transport properties of CaAl2Si2O8 liquid. Part I: Molecular dynamics simulations

Structure, thermodynamics, and diffusion in CaAl2Si2O8 liquid from first-principles molecular dynamics

“…(14), with k computed from the parameterized potential results of Spera et al (2009). Finite size effects are found to be very small for D(O), but self-diffusivities for D(Ca), D(Al), and D(Si) are underestimated by about 15-20%.…”

“…Previous theoretical studies used parameterized potential simulations, and revealed a number of interesting phenomena (e.g. Angell et al, 1982;Nevins and Spera, 1998;Ghiorso et al, 2009;Spera et al, 2009). However, the reliability of these results is difficult to judge, owing to the simplicity of the bonding representation used.…”

Simplicity in melt densification in multicomponent magmatic reservoirs in Earth’s interior revealed by multinuclear magnetic resonance

“…Although the trend in the silica activity in the melts at high pressure is not known, phase relations of mantle melts and minerals imply varying activity coefficients of the oxide in silicate melts with changes in pressure (12)(13)(14). Changes of up to two orders of magnitude in the element partitioning coefficient between melts and crystal/coexisting phases have been reported stemming mostly from the effect of the melt composition, constraining the fate of radioactive nuclides in the Earth's interior (15-18).The key to understanding these nonlinear changes in melt properties with pressure is the melt structure at high-pressure in a short-(e.g., coordination number) to medium-range scale (19)(20)(21). While recent progress in mineral physics provides the link between the macroscopic properties and the structures of the crystals, the nature of changes in the melt structure at high pressures, such as those deep within the magma-ocean, remain poorly constrained as detailed knowledge about the structure of melts cannot be determined based on their compositions alone.…”

“…The key to understanding these nonlinear changes in melt properties with pressure is the melt structure at high-pressure in a short-(e.g., coordination number) to medium-range scale (19)(20)(21). While recent progress in mineral physics provides the link between the macroscopic properties and the structures of the crystals, the nature of changes in the melt structure at high pressures, such as those deep within the magma-ocean, remain poorly constrained as detailed knowledge about the structure of melts cannot be determined based on their compositions alone.…”

A self-consistent optimization of multicomponent solution properties: Ab initio molecular dynamic simulations and the MgO–SiO2 miscibility gap under pressure

“…Moreover, previous classical MD simulations of MgO-SiO 2 melts (Belonoshko and Dubrovinsky, 1996a;Oganov et al, 2000;Ben Martin et al, 2009;Spera et al, 2011) did not explore the entire range of composition and do not address the present issue. Other classical MD simulations have been performed on geologically relevant multicomponent compositions (Matsui et al, 2000;Guillot and Sator, 2007;Spera et al, 2009;Ben Martin et al, 2012) but in each case these studies examined only the thermo-physical properties of specific melt compositions and not excess properties of the solutions.…”