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中文摘要：
采用零温条件下的赝势-平面波方法和有限温度下的Car-Parrinello分子动力学方法，模拟了不同压力环境下氦原子在金属铌中的行为特征，研究了宿主缺陷和氦泡的形成机制。结果表明，闭电子壳层的氦原子在金属铌中具有刚球模型特征，其占据区域为金属自由电子的禁区，从而破坏铌原子之间的金属性键合。在常温条件下，局域高浓度的氦原子优先凝聚于近邻宿主空位缺陷处，从而形成氦泡；完整晶格中高浓度的氦将促使铌原子易位，形成间隙一空位模式的宿主缺陷，氦原子聚集于空位区域。完整宿主在压力（40GPa）的作用下，晶格参数减小，铌原子之间的相互作用增强，尽管氦原子的存在削弱了铌原子之间的相互作用，位于格点上的铌原子仍难以借助热振动偏离格点形成空位，因而未能形成间隙-空位对和氦泡。
英文摘要：
By combining pseudopotential plane-wave method at 0 K with Car-Parrinello molecular dynamics at finite temperature, the behavior and aggregation of helium in niobium are simulated under different pressures. The result shows that the closed-shell helium atom plays a role of rigid-ball such that to destroy local metallic bonds of niobium and push away the near free electrons. Under ambient pressure and room temperature, locally high concentrated helium atoms immigrate towards the vacancy site, resulting in helium bubbles. The same helium density of He will dislocate Nb atom, forming an in- terstitial-vacancy pair for the helium bubble formation. Under high pressures up to 40 GPa,no bubble is observed in perfect Nb host lattice due to the failure of interstitial-vacancy formation.
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