高温高压下黄铁矿热力学性质的第一性原理研究

黄铁矿是自然界中分布最为广泛的硫化物矿物,同时也是重要的造矿矿物,在金属矿床、沉积岩、变质岩、花岗岩、基性-超基性岩浆岩、以及地幔岩中都有大量出现。因此,研究黄铁矿在不同温度压力下的热力学性质可以为深入探讨与黄铁矿有关的成岩、成矿、成藏问题提供有用的矿物学依据。本文利用基于密度泛函微扰理论的第一性原理方法,采用准谐近似计算了黄铁矿在高温高压下的热力学性质。我们计算的黄铁矿的晶格常数、零压下的体积模量及其对压力的导数与前人的实验及理论计算结果吻合得很好,零压下等压热容和熵随温度的变化与实验结果有很好的一致性。尤其是,本文计算了直至2500K、100GPa的高温高压下黄铁矿的等温体积模量、热膨胀系数、热容和熵等热力学性质。这为在有硫参与的情况下,人们开展下地壳-岩石圈地幔深度的地球动力学模拟和建立地球物理模型提供了有用的信息。

First-principles study of thermodynamic properties of pyrite under high pressure and temperature

Pyrite (FeS₂) is the most abundant metal sulfide mineral in nature and occurs in a wide range of geological environments (e.g., metallic mineral deposits, sedimentary rocks, metamorphic rocks, granite, basic-ultrabasic magmatic rocks, and pyrolite). In order to know the pressure-thermodynamic properties and temperature-thermodynamic properties of pyrite, which is very important to understand the diagenesis, mineralization and reservoir forming about pyrite, a quasi-harmonic approximation and first-principles study of thermodynamic properties of FeS₂ under high pressure and temperature is performed by density functional perturbation theory. The lattice constants, zero-pressure bulk modulus and its pressure of derivatives are in good agreement with previous experimental and theoretical values, and the isobaric heat capacity and entropy are consistent with the available experimental data exactly. We calculate the thermodynamics properties, including isothermal bulk modulus, coefficient of thermal expansion, heat capacity and entropy of pyrite under high pressure (100GPa) and temperature (2500K). This can provide useful information for the establishment of geophysical model and numerical simulation of geodynamic processes at the depth of lower crust-lithospheric mantle with the presence of sulfur.