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钾钡共掺菲分子结构和电子特性的第一性原理研究
引用本文:轩书科.钾钡共掺菲分子结构和电子特性的第一性原理研究[J].物理学报,2017,66(23):237401-237401.
作者姓名:轩书科
作者单位:山东工艺美术学院公共课教学部, 济南 250300
摘    要:采用基于密度泛函理论的平面波赝势法,对钾钡共掺杂情形下菲分子晶体的结构、能带、电子态密度、形成能、电荷转移等电子特性进行系统的研究.通过对比计入范德瓦尔斯力作用前后晶体结构的差异,说明计算中包含范德瓦尔斯力修正的重要性.从形成能的角度证明了共掺杂的可行性和稳定性.在钾钙、钾锶、钾钡等共掺杂元素组合中,K_1Ba_1-菲中平均每个金属原子的形成能为-0.25 eV,远大于K_1Sr_1-菲和K_1Ca_1-菲中的-0.13和-0.04 eV,钾钡共掺杂是最合理的方案.只有单双价金属共掺杂,才能使分子呈现负三价.此时,菲分子最低未占据轨道(LUMO)和LUMO+1轨道组成的能带正好位于费米能级处,K_1Ba_1-菲呈现金属性.费米能级处的态密度为17.3 eV~(-1),电子态主要来自于碳原子的2p轨道,钡原子的5d轨道也有少许贡献.从理论模拟的角度研究了K_1Ba_1-菲的晶体结构和电子特性,在已有实验和理论研究尚未涉及共掺杂的背景下,提出了不同价态金属共掺杂方案,为制备芳烃有机超导体样品和调制体系电子结构提供了新的研究思路.

关 键 词:电子结构  第一性原理  有机超导体  芳香烃
收稿时间:2017-03-10

First principles studies on molecular structure and electronic properties of K- and Ba-codoped phenanthrene
Xuan Shu-Ke.First principles studies on molecular structure and electronic properties of K- and Ba-codoped phenanthrene[J].Acta Physica Sinica,2017,66(23):237401-237401.
Authors:Xuan Shu-Ke
Institution:School of Common Courses, Shandong University of Art and Design, Ji'nan 250300, China
Abstract:The superconductivity has always been one of the important topics in condensed matter physics. Recently, the discovery of superconductivity in potassium-doped picene have opened the way to a new class of organic superconductor, and at the same time metal-doped aromatic hydrocarbons have attracted great interest of researchers in investigating their physical and chemical properties. In this paper, according to the plane wave and pseudopotential method in the framework of density functional theory, we systematically study the structural and electronic properties of the K/Ba-codoped phenanthrene, including the atomic structure, band structure, density of states, formation energy, and charge transfer between dopant and phenanthrene molecule, and three meaningful conclusions have been drawn as follows. At first, the van der Waals interaction is found to play an important role in determining the atomic structure of metal-doped molecular solid, so it is necessary to include the interactions in these calculations. Secondly, due to the similarity in ionic radius, the combination of K and Ba is the favorable scheme for multiple-metal codoped phenanthrene crystal compared with K/Ca and K/Sr codoping schemes. From the viewpoint of formation energy, K1Ba1-phenanthrene has a bigger formation energy (-0.25 eV) per doped metal atom than K1Sr1-phenanthrene (-0.13 eV) and K1Ca1-phenanthrene (-0.04 eV). Thirdly, in order to realize the -3 valent state of phenanthrene molecule in K/Ba-codoped phenanthrene, the codoping of monovalent and bivalent metals is the only viable option due to the narrow interstitial space in molecular crystal. The bands crossing the Fermi level are from the lowest unoccupied molecular orbital (LUMO) and LUMO+1 orbital, resulting in the metallic state of K1Ba1-phenanthrene. The large density of states at the Fermi level is 17.3 eV-1, and these electronic states are mainly from C 2p orbitals and a little contribution from Ba 5d orbitals. Our studies present the electronic structure of K1Ba1-phenanthrene and suggest that K/Ba-codoping is a rational scheme to synthesize the superconductive sample, which provides a new route to the exploration of the promising superconductivity in metal-doped aromatic hydrocarbons.
Keywords:electronic structure  first principles  organic superconductor  aromatic hydrocarbon
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