论文标题
$ {\ text {c}} _ {60} $ fullerene几何形状的反铁磁性$ s = 1/2 $ heisenberg模型
The antiferromagnetic $S=1/2$ Heisenberg model on the ${\text{C}}_{60}$ fullerene geometry
论文作者
论文摘要
我们使用密度 - 矩阵恢复归一化组（DMRG）解决了旋转位于截短的Icosahedron的顶点上的旋转的量子机械抗磁性海森堡模型。这描述了未掺杂的c $ _ {60} $ fullerene的磁性特性，半填充了强度的现场交互$ u $。我们计算所有可能的距离，最低的单线和三重态激发态以及热力学特性的基态和相关函数，即特定的热和自旋敏感性。 我们发现，与较小的C $ _ {20} $或C $ _ {32} $可以通过确切的对角度解决的方法不同，最低的兴奋状态是一个三胞胎而不是单人，这表明由于许多六角形面孔的存在和类似于五角形的面孔而导致的挫败感减少，并且与tern不平的面孔相似，因此发现了ternunced for for the Trunced for for Trunced tetrend。这意味着挫败感可能会通过改变尺寸而在富勒伦中进行调谐。 自旋旋转相关性沿着六角形键更强，并且随距离呈指数减小，因此该分子足够大，以至于不在整个范围内相关。特定的热量显示高温峰和低温的肩膀让人联想到kagome晶格，而自旋敏感性显示出一个宽峰，并且非常接近C $ _ {20} $中的一个。
We solve the quantum-mechanical antiferromagnetic Heisenberg model with spins positioned on vertices of the truncated icosahedron using the density-matrix renormalization group (DMRG). This describes magnetic properties of the undoped C$_{60}$ fullerene at half filling in the limit of strong on-site interaction $U$. We calculate the ground state and correlation functions for all possible distances, the lowest singlet and triplet excited states, as well as thermodynamic properties, namely the specific heat and spin susceptibility. We find that unlike smaller C$_{20}$ or C$_{32}$ that are solvable by exact diagonalization, the lowest excited state is a triplet rather than a singlet, indicating a reduced frustration due to the presence of many hexagon faces and the separation of the pentagonal faces, similar to what is found for the truncated tetrahedron. This implies that frustration may be tuneable within the fullerenes by changing their size. The spin-spin correlations are much stronger along the hexagon bonds and exponentially decrease with distance, so that the molecule is large enough not to be correlated across its whole extent. The specific heat shows a high-temperature peak and a low-temperature shoulder reminiscent of the kagome lattice, while the spin susceptibility shows a single broad peak and is very close to the one of C$_{20}$.
