Abstract

We employed first-principles density-functional theory (DFT) calculations to characterize Dirac electrons in quasi-two-dimensional molecular conductor \(\alpha \)-(BETS)\(_2 \hbox {I}_3\) [= \(\alpha \)-(BEDT–TSeF)\(_2 \hbox {I}_3\)] at a low temperature of 30 K. We provide a tight-binding model with intermolecular transfer energies evaluated from maximally localized Wannier functions, where the number of relevant transfer integrals is relatively large due to the delocalized character of Se p orbitals. The spin–orbit coupling gives rise to an exotic insulating state with an indirect band gap of about 2 meV. We analyzed the energy spectrum with a Dirac cone close to the Fermi level to develop an effective Hamiltonian with site potentials, which reproduces the spectrum obtained by the DFT band structure.

Graphic abstract

中文翻译：

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二维分子导体$$ \ alpha $$α-（BETS）$$ _ 2 \ hbox {I} _3 $$ 2 I 3中具有自旋轨道耦合的狄拉克费米子有效哈密顿量的第一性原理研究

摘要

我们采用第一原理密度泛函理论（DFT）计算来表征准二维分子导体\（\ alpha \） -（BETS）\（_ 2 \ hbox {I} _3 \） [= \（ \ alpha \） -（BEDT–TSeF）\（_ 2 \ hbox {I} _3 \） ]在30 K的低温下。我们提供了一种具有分子间转移能的紧密结合模型，该模型由最大局部的Wannier函数评估，其中由于Se p的离域特征，相关传递积分的数量相对较大轨道。自旋轨道耦合产生了一种奇特的绝缘状态，其间接带隙约为2 meV。我们用接近费米能级的狄拉克锥分析了能谱，以开发出具有位势的有效哈密顿量，从而再现了通过DFT能带结构获得的光谱。

图形摘要