Single-site DFT+DMFT for vanadium dioxide using bond-centered orbitals

We present a combined density-functional theory and single-site dynamical mean-field theory (DMFT) study of vanadium dioxide (VO₂) using an unconventional set of bond-centered orbitals as the basis of the correlated subspace. VO₂ is a prototypical material undergoing a metal-insulator transition (MIT), hosting both intriguing physical phenomena and the potential for industrial applications. With our choice of correlated subspace basis, we investigate the interplay of structural dimerization and electronic correlations in VO₂ in a computationally cheaper way compared to other state-of-the-art methods, such as cluster DMFT. Our approach allows us to treat the rutile and M1 monoclinic VO₂ phases on an equal footing and to vary the dimerizing distortion continuously, exploring the energetics of the transition between the two phases. The choice of basis presented in this work hence offers a complementary view on the long-standing discussion of the MIT in VO₂ and suggests possible future extensions to other similar materials hosting molecular-orbital-like states.

本项研究综合运用了密度泛函理论（DFT）与单点动力学平均场理论（DMFT），以一组非传统的以键为中心的轨道作为相关子空间的基，对二氧化钒（VO₂）进行了深入研究。VO₂作为一种典型的金属-绝缘体转变（MIT）材料，不仅蕴含着引人入胜的物理现象，而且具有潜在的工业应用价值。我们选取的相关子空间基，相较于其他最先进的方法，如簇DMFT，以更低计算成本探究了VO₂中结构二聚化与电子关联的相互作用。该方法使我们能够平等地处理金红石相和M1单斜相的VO₂，并连续改变二聚化畸变，研究两种相之间的能级转换。本研究中提出的基的选择，因此为VO₂中关于MIT的长期讨论提供了补充视角，并暗示了可能对未来其他类似材料（其具有类似分子轨道的状态）的研究拓展。