Abstract: Effect of external high pressure on crystal structure of pyrite (FeS2) has been simulated by using abinitio norm-conserving pseudo-potential plane wave molecular dynamic method based on density functional theory, within the general gradient density approximation. The calculation of energy band structure and the density of state for strained pyrite shows that structural strain leads to the increase of pyrite Fermi energy (EF). In addition, according to transitional state theory,mechanical activation promotes the rate constant of chemical reaction, which is equivalent to exchange current density in the field of corrosion electrochemistry. According to energy band model of semiconductor and mixed potential model of corrosion electrochemistry, the corrosion current of pyrite increases with the increase of pyrite Fermi energy(EF) and exchange current density, that is, the rate of dissolution increases. Thus it is concluded that the mechanically active phenomenon of pyrite not only involves mechanism of mechanical chemistry, but also mechanism of mechanical electrochemistry.
Computational simulation to mechanical activation of pyrite (Ⅰ) ——Relation of structural strain to chemistry reaction activity
Abstract:
Effect of external high pressure on crystal structure of pyrite (FeS 2) has been simulated by using abinitio norm conserving pseudo potential plane wave molecular dynamic method based on density functional theory, within the general gradient density approximation. The calculation of energy band structure and the density of state for strained pyrite shows that structural strain leads to the increase of pyrite Fermi energy ( E F) . In addition, according to transitional state theory, mechanical activation promotes the rate constant of chemical reaction, which is equivalent to exchange current density in the field of corrosion electrochemistry. According to energy band model of semiconductor and mixed potential model of corrosion electrochemistry, the corrosion current of pyrite increases with the increase of pyrite Fermi energy ( E F) and exchange current density, that is, the rate of dissolution increases. Thus it is concluded that the mechanically active phenomenon of pyrite not only involves mechanism of mechanical chemistry, but also mechanism of mechanical electrochemistry.
Fig.2 Effect of structural strain on state density of pyrite
(a) —Decreasing a0; (b) —Decreasing XS; (c) —Decreasing a0 and XS (The solid curve shows state density of unstrained pyrite, while the dotted curve is state density of strained pyrite)
图3 黄铁矿/溶液界面能带模型
Fig.3 Energy band diagram at pyrite-solution interface
图4 黄铁矿氧化溶解的混合电位模型
Fig.4 Mixed potential model of pyrite oxido-dissolution by oxygen