极端情况下材料的物性研究是当今凝聚态材料的研究前沿，而高压情况下的物性研究更是其中重要研究热点。由于实验条件和设备的限制，对于极端情况的材料性质的研究仍存在很大的困难，而计算物理的飞速发展为此方面研究提供了有效合理的研究途径，尤其是第一性原理计算方法，广泛应用于材料物理的定量计算及分析研究。 本文采用基于密度泛函理论(DFT)的平面波赝势方法的第一性原理计算，对过渡金属铜元素进行总能量计算，能量计算精度取为0.01eV/atom。通过分析分波能带展宽与能带电子对总能量的贡献，讨论了不同压强范围下第一性原理计算时铜原子芯态和价态的划分。结果显示，当压强增加到约139.3GPa时，3p电子因能带的展宽对总能的贡献将不能忽略，需将作为价电子处理。计算结果为进一步高压下的物性的第一性原理研究提供了依据。

Physical properties at the extreme conditions have attracted considerable interests, especially at the high-presssures. At present, as the restriction of experimental conditions, the studies at these extreme conditions, however, are still far from routine, while the fast developments of the computational physics provide an effective and reasonable investigative approach. The first-principles calculations have now extensively applied to study material properties. In this paper, first-principles calculations method based on the density-functional theory(DFT), employing the pseudopotentionals and plane-wave method, are performed for the total energy calculations of the transition metal copper. We set the computational precision of the energy to 0.0ｌeV/atom and do the total-energy calculations.The calculated results show that the 3p state should be treated as valence state when pressure is higher than 139.3GPa.