First-Principles Study of the Equation of Statefor Uranium under High Pressures
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摘要: 利用基于密度泛函理论的赝势平面波方法，研究了铀的状态方程。基态计算结果表明：在100GPa的压强范围内，α-U结构是最稳定的相。利用量子分子动力学方法(QMD)，计算了有限温度下的状态方程，在此基础上计算了冲击Hugoniot点，并与实验数据及其他理论计算结果进行了比较，结果表明：在100GPa以下的压力区域内，QMD计算结果与实验结果符合得很好，而用快速计算状态方程(QEOS)方法计算的结果偏软。Abstract: In this paper we studied the equation of state (EOS) of uranium using the first-principles.The calculation of ground states indicates that the α structure is the most stable phase.The EOS at finite temperatures was computed by the quantum molecular dynamics (QMD).Based on this, the Hugoniot data were calculated and compared with the experimental data and other theoretical results.When the pressure is below 100GPa, the QMD calculated results are in good agreement with the experimental data, while those from the calculation by the quotidian equation of state (QEOS) don't agree so well with the experimental results.
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Key words:
- uranium /
- equation of state /
- first-principle
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图 1 不同结构铀的原子总能与原子体积的关系
Figure 1. Total atomic energies vs.atomic volumesfor various structures of uranium
图 2 不同结构铀的冷压与原子体积的关系
Figure 2. Cold pressures vs.atomic volumesfor various structures of uranium
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