论文标题
来自准自由稳定的g $ _0 $ w $ _0 $的电子结构$ _2 $
Electronic structure of TiSe$_2$ from a quasi-self-consistent G$_0$W$_0$ approach
论文作者
论文摘要
在先前的工作中，证明了精确交换的包含对于对tise $ _2 $的电子和振动特性的第一原理描述至关重要。 [物理。莱特牧师。 119，176401（2017）]。 $ GW $近似提供了无参数的筛选交换描述，但通常是扰动（$ g_0w_0 $）的使用，使结果或多或少地依赖于起点。在这项工作中，我们根据随机相位近似（RPA）和混合密度功能理论的优化有效潜力开发出$ g_0w_0 $的准自由抗性扩展。此方法生成了最佳的$ G_0W_0 $起点和与RPA一致的混合交换参数。虽然自矛盾在AR，BN和SCN等系统中起较小的作用，但事实证明这对于Tis $ _2 $和TISE $ _2 $至关重要。我们发现Tise $ _2 $的高温阶段是半金属的，带有与实验非常吻合的频带结构。此外，优化的混合功能与我们先前的估计值很好地吻合，因此准确地再现了低温电荷密度波相。
In a previous work it was shown that the inclusion of exact exchange is essential for a first principles description of both the electronic- and the vibrational properties of TiSe$_2$, M. Hellgren et al. [Phys. Rev. Lett. 119, 176401 (2017)]. The $GW$ approximation provides a parameter-free description of screened exchange but is usually employed perturbatively ($G_0W_0$) making results more or less dependent on the starting point. In this work, we develop a quasi-self-consistent extension of $G_0W_0$ based on the random phase approximation (RPA) and the optimized effective potential of hybrid density functional theory. This approach generates an optimal $G_0W_0$ starting-point and a hybrid exchange parameter consistent with the RPA. While self-consistency plays a minor role for systems such as Ar, BN and ScN, it is shown to be crucial for TiS$_2$ and TiSe$_2$. We find the high-temperature phase of TiSe$_2$ to be a semi-metal with a band structure in good agreement with experiment. Furthermore, the optimized hybrid functional agrees well with our previous estimate and therefore accurately reproduces the low-temperature charge density wave phase.
