arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 1105.0198cond-mat.mtrl-sci
收藏

关联金属LaNiO $_3$的晶格简正模和电子性质

Lattice normal modes and electronic properties of the correlated metal LaNiO$_3$

Gaoyang Gou, Ilya Grinberg, Andrew M. Rappe, James M. Rondinelli

摘要:

我们利用密度泛函理论(DFT)研究了关联金属LaNiO $_3$的晶格振动和电子性质.为了表征钙钛矿型LaNiO $_3$的菱面体到立方结构的相变,我们研究了拉曼活性声子模式随温度的演化。我们发现,$A_{1g}$拉曼模式,其频率是敏感的电子能带结构,是一个有用的签名来表征菱面体LaNiO $_3$的八面体旋转。我们还研究了电子-电子关联效应对原子结构的重要性,这超出了传统的能带理论(局域自旋密度近似)的两种方法:局域自旋密度+Hubbard $U$方法(LSDA $+U$)和混合交换相关密度泛函,其中包括部分确切的Fock交换。我们发现,传统的LSDA准确地再现了LaNiO $_3$的价态的离域性质,并给出了最好的结构和振动协议,现有的实验数据。计算结果表明,离域Ni 3 $d$和O-2 $p$态的电子屏蔽效应减弱了$d^7$ Ni阳离子的电子关联,使LaNiO $_3$成为弱关联金属.

英文摘要:

We use density functional theory (DFT) calculations to study the lattice vibrations and electronic properties of the correlated metal LaNiO$_3$. To characterize the rhombohedral to cubic structural phase transition of perovskite LaNiO$_3$, we examine the evolution of the Raman-active phonon modes with temperature. We find that the $A_{1g}$ Raman mode, whose frequency is sensitive to the electronic band structure, is a useful signature to characterize the octahedral rotations in rhombohedral LaNiO$_3$. We also study the importance of electron--electron correlation effects on the atomic structure with two approaches which go beyond the conventional band theory (local spin density approximation): the local spin density+Hubbard $U$ method (LSDA$+U$) and hybrid exchange-correlation density functionals which include portions of exact Fock-exchange. We find the conventional LSDA accurately reproduces the delocalized nature of the valence states in LaNiO$_3$ and gives the best structural and vibrational agreement to the available experimental data. Based on our calculations, we show that the electronic screening effect from the delocalized Ni 3$d$ and O-2$p$ states mitigate the electronic correlations of the $d^7$ Ni cations, making LaNiO$_3$ a weakly correlated metal.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑