透過第一原理計算，我們研究了BiSc在不同應變下的能帶結構和拓撲不變量。我們討論的應變範圍是-5%到+5%。隨著應變增加，Γ點會打開能隙，而X點的能隙由大變小，能隙關閉後再由小變大，經歷了能帶反轉。結果，BiSc從金屬轉變為拓撲絕緣體，然後從拓撲絕緣體轉變為一般絕緣體。另一方面，我們也討論了自旋軌道耦合對不同拓撲結構的影響。隨著自旋軌道耦合的強度增加，如果X點有經歷能帶反轉，那麼就會是拓撲絕緣體，否則，就會是一般絕緣體。

Using the first-principles calculation, we studied the band structure and topological invariants of BiSc under different strains. The strain range we discussed is -5% to +5%. With further increase of the strain, the energy gap at the Γ point will open, the energy gap at the X point will decrease to zero and then increase, band inversion appears at the X point. Consequently, BiSc has undergone the transition from metal to topological insulator and topological insulator to normal insulator. On the other hand, we also discussed the effect of spin-orbit coupling on different topologies. As the spin-orbit coupling strength increases, if the X point undergoes a band inversion, then it will be a topological insulator, otherwise, it will be a normal insulator.

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