Alkali-doped fullerides show a wide range of electronic phases in function of alkali atoms and the degree of doping. Although the presence of strong electron correlations is well established, recent investigations also give evidence for dynamical Jahn-Teller instability in the insulating and the metallic trivalent fullerides. In this work, to reveal the interplay of these interactions in fullerides with even electrons, we address the electronic phase of tetravalent fulleride with accurate many-body calculations within a realistic electronic model including all basic interactions extracted from first principles. We find that the Jahn-Teller instability is always realized in these materials too. In sharp contrast to the correlated metals, tetravalent system displays uncorrelated band-insulating state despite similar interactions present in both fullerides. Our results show that the Jahn-Teller instability and the accompanying orbital disproportionation of electronic density in the degenerate lowest unoccupied molecular orbital band is a universal feature of fullerides.

中文翻译：

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电子密度的轨道歧化是碱掺杂的富勒化物的普遍特征。

掺杂碱金属的富勒化物显示出广泛的电子相，这些电子相具有碱原子和掺杂程度的作用。尽管已经很好地确定了强电子相关性的存在，但最近的研究也为绝缘和金属三价富勒物中的动态Jahn-Teller不稳定性提供了证据。在这项工作中，为了揭示这些相互作用在富勒分子与偶数电子之间的相互作用，我们在一个实际的电子模型中，包括从第一原理中提取的所有基本相互作用，通过精确的多体计算来解决四价富勒酸酯的电子相。我们发现，在这些材料中也始终可以实现Jahn-Teller不稳定性。与相关金属形成鲜明对比的是，尽管两个富勒烯中都存在相似的相互作用，但四价体系仍显示出不相关的带绝缘状态。我们的结果表明，简并最低的未占据分子轨道带中的Jahn-Teller不稳定性以及伴随的电子密度的轨道失配是富勒分子的普遍特征。