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首页> 外文期刊>Physics of the Earth and Planetary Interiors: A Journal Devoted to Obsevational and Experimerntal Studies of the Chemistry and Physics of Planetary Interiors and Their Theoretical Interpretation >A computer simulation study of the effect of pressure on Mg diffusion in forsterite
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A computer simulation study of the effect of pressure on Mg diffusion in forsterite

机译：压力对镁橄榄石中镁扩散影响的计算机模拟研究

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Computer simulation techniques were used to investigate the effect of pressure on magnesium diffusion in forsterite between 0 and 10 GPa. We studied the diffusion path along the c crystallographic axis (we always refer to the Pbnm system) via a vacancy mechanism. Using a Mott-Littleton approach within the code GULP, we were able to precisely map the diffusion path of a Mg vacancy and we found the activation energy, E = 3.97 eV at 0 GPa (with E-f = 3.35 eV for the formation energy and E-m = 0.62 eV for the migration) and E = 4.46eV at 10GPa (E-f = 3.81 eV and E-m = 0.65eV). Preliminary results using the supercell technique gave the same saddle point coordinates and energies. This saddle point of the Mg vacancy diffusion found with GULP was then introduced in an ab initio code, confirming the values of the migration energy both at 0 and 10GPa. We were therefore able to estimate the activation volume (Delta V) to be around 5 cm(3)/mol and d(Delta V)/dP similar or equal to 0. The effect of pressure applies mostly on defect formation and little on migration.
机译：使用计算机模拟技术来研究压力对0-10 GPa之间镁橄榄石中镁扩散的影响。我们通过空位机制研究了沿c晶轴（我们始终指的是Pbnm系统）的扩散路径。使用代码GULP中的Mott-Littleton方法，我们能够精确地映射Mg空位的扩散路径，我们发现0 GPa时的活化能E = 3.97 eV（对于地层能量和Em，Ef = 3.35 eV迁移时= 0.62 eV）和10GPa时E = 4.46 eV（Ef = 3.81 eV和Em = 0.65eV）。使用超级电池技术的初步结果给出了相同的鞍点坐标和能量。然后，将用GULP发现的镁空位扩散的鞍点引入从头算代码，从而确认了0GPa和10GPa时的迁移能值。因此，我们能够估计活化体积（Delta V）约为5 cm（3）/ mol，d（Delta V）/ dP大约等于或等于0。压力的影响主要应用于缺陷的形成，而对迁移的影响很小。 。

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