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使用第一性原理方法结合准谐近似理论研究了立方结构钨的热力学性质,包括平衡体积V、体弹模量B0、线膨胀系数α、熵S、振动自由能F、等压热容CP和等容热容CV随温度的变化关系。在计算体系的线膨胀系数、熵、振动自由能、等压热容和等容热容时考虑了热电子和热振动对自由能的贡献。计算结果表明:考虑热电子对自由能贡献后得到的线膨胀系数、熵、振动自由能和等压热容在0～2000 K范围内均与实验值符合较好。在得到平衡体积随温度变化的基础上,计算了钨立方结构的弹性性质,得到了弹性常数、体积模量、剪切模量和杨氏模量随温度的变化关系,所得结果与实验测量值符合较好。
The thermodynamic properties of cubic tungsten, such as equilibrium volume V, bulk modulus B0, coefficient of linear expansion α, entropy S, vibrational free energy F, isobaric heat capacity CP and Equivalent heat capacity CV with the temperature changes. The contribution of thermal electron and thermal vibration to free energy is taken into account when calculating the linear expansion coefficient, entropy, free energy of vibration, isobaric heat capacity and isochoric heat capacity. The calculated results show that the linear expansion coefficient, entropy, vibrational free energy and isobaric heat capacity are in good agreement with the experimental data in the range of 0 ~ 2000 K, considering the contribution of thermal electrons to free energy. Based on the change of equilibrium volume with temperature, the elastic properties of tungsten cubic structure were calculated and the relationship between elastic constants, bulk modulus, shear modulus and Young’s modulus with temperature was obtained. The obtained results were compared with the experimental values In line with the better.