Generalized Stone-Wales transformation as the possible origin of ferromagnetism in polymeric C60: a density-functional theory study.
Generalized Stone-Wales transformation as the possible origin of ferromagnetism in polymeric C60: a density-functional theory study.
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广义斯通-威尔士变换作为聚合物 C60 中铁磁性的可能起源：密度泛函理论研究。
DOI：
10.1063/1.2388258
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发表时间：
2006
影响因子：
4.4
通讯作者：
J. Novoa
中科院分区：
文献类型：
--
作者：
J. Ribas‐Ariño;J. Novoa
最近，有一个建议[Y。H. Kim等人，Phys. Rev. B 68，125420（2003）]，表明压缩和加热的聚合物-C（60）固体中的铁磁相互作用可能是由于存在三重态开笼，其由C（60）笼内的连续广义Stone-Wales变换产生。在这里，通过执行B3 LYP 3 - 21 G和B3 LYP 6 - 31 G（d）优化，我们对这些开笼在其闭壳层单重态、开壳层单重态和三重态的生成机制的热力学和动力学进行了系统的研究。我们还计算了由三重态基态的开笼引起的磁相互作用。我们的结果表明，这种机制不适合解释压缩和加热的聚合物C（60）中发现的铁磁性，原因如下：（a）形成唯一呈现三重基态的开笼需要超过318 kcal/mol的最高能量点，远高于文献中报道的其他竞争机制;形成的三重态开放笼对于它们转变成抗磁性中间体是不稳定的;（c）两个相邻三重态开放笼之间的磁性相互作用是反铁磁性的。
Recently, there has been a proposal [Y.-H. Kim et al., Phys. Rev. B 68, 125420 (2003)] suggesting that ferromagnetic interactions in compressed and heated polymeric-C(60) solids could be due to the existence of triplet open cages resulting from successive generalized Stone-Wales transformations within the C(60) cage. Here, by performing B3LYP3-21G and B3LYP6-31G(d) optimizations, we carried out a systematic investigation of the thermodynamics and kinetics of the mechanism of generation of these open cages in their closed-shell singlet, open-shell singlet, and triplet states. We also computed the magnetic interactions induced by the open cages presenting a triplet ground state. Our results indicate that this mechanism is not appropriate to explain the ferromagnetism found in compressed and heated polymeric C(60) for the following reasons: (a) the formation of the only open cage presenting a triplet ground state requires overpassing a highest energy point of 318 kcal/mol, well above other competitive mechanisms reported in the literature; the triplet open cages formed are not stable against their transformation into a diamagnetic intermediate; (c) the magnetic interactions between two adjacent triplet open cages are antiferromagnetic.