由P. C. Donohue與P. E. Bierstedt於1969年所發表的論文中表明NbPS、TaPS、NbPSe的超導性質[1]，1999年由Ichimin Shirotani發表的實驗結果也探討了NbPS的電聲子交互作用係數[2]。我們以第一原理以及密度泛函微擾理論研究這些材料的電聲子結構與超導性質，在NbPS的研究中，我們計算所得到的超導臨界溫度為15K，與Donohue和Bierstedt的實驗結果12K相近，而電聲子交互作用係數的計算結果(λ=1.01)也與Ichimin Shirotani等人的實驗結果(λ=0.81)差異不大。在TaPS、NbPSe的研究中，我們分別得到11K、6K的超導臨界溫度，然而，在Donohue與Bierstedt的論文中提到溫度降至1.25K皆未出現超導現象。除超導的研究以外，我們從它們的能帶結構中看出疑似有能帶反轉的現象。NbPS、TaPS、NbPSe的晶體結構相同，電子結構也相近，我認為它們會有相似的超導性質，然而，近年只有NbPS有新的實驗證據，因此，我認為要有新的實驗確認TaPS與NbPSe是否有超導現象，並以其他的研究確認是否是拓樸材料。

Superconductivity of ternary compounds NbPS, TaPS and NbPSe have been studied with experiments in 1969 by P. C. Donohue and P. E. Bierstedt [1]. The electron-phonon constant of NbPS was also reported by Ichimin Shirotani in 1999 [2]. We use density functional perturbation theory to calculate electron-phonon interaction and superconducting properties of these compounds. On the study of NbPS, we found the electron-phonon constant λ=1.01 and the critical temperature T_c=15K, which are consistent with the result of experiments (λ=0.81, T_c=12K). In addition, the results of our calculation show that TaPS and NbPSe are also superconductors. However, they do not show superconductivity down to 1.25K in experiments done by Donohue and Bierstedt. We also found band inversion in the materials. We suggest more experience to check superconducting properties of these materials, and more research to confirm whether they are topological materials or not.

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