Two-dimensional (2D) transition metal dichalcogenides (TMDs) exhibit diverse functionalities owing to their highly tunable chemical, physical, and electronic attributes. In this study, we systematically investigate the structural, electronic, and phonon responses of six TMD systems using density functional theory (DFT) simulations. Our analysis unveils a reversible phase transition between the semiconducting (2H) and metallic (1T) phases within the stable phases of these TMD systems. Specifically, group-V TMDs (AB 2, where A = Nb, Ta and B = S, Se, Te) systems are focused in the present calculations. Their electronic behavior has been evaluated to validate the accuracy of several available exchange-correlation (XC) functionals, along with van der Waals density functionals (vdW-DFs). Both spin-orbit coupling (SOC) effects and non-SOC (NSOC) cases are considered in our calculations. Notable changes in the electronic band structure and density of states between the 2H and 1T phases underscore their potential utility in conventional device applications.

中文翻译：

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评估范德华 TMD 材料 AB2 中的准确交换相关函数（A = Nb、Ta 和 B = S、Se、Te）

二维（2D）过渡金属二硫属化物（TMD）由于其高度可调的化学、物理和电子属性而表现出多种功能。在这项研究中，我们使用密度泛函理论 (DFT) 模拟系统地研究了六个 TMD 系统的结构、电子和声子响应。我们的分析揭示了这些 TMD 系统稳定相内半导体 (2H) 和金属 (1T) 相之间的可逆相变。具体而言，本计算重点关注 V 族 TMD（AB 2，其中 A = Nb、Ta 和 B = S、Se、Te）系统。它们的电子行为已经过评估，以验证几种可用的交换相关 (XC) 泛函以及范德华密度泛函 (vdW-DF) 的准确性。我们的计算中同时考虑了自旋轨道耦合 (SOC) 效应和非 SOC (NSOC) 情况。 2H 和 1T 相之间电子能带结构和态密度的显着变化强调了它们在传统器件应用中的潜在用途。