Computational quantum chemistry for single Heisenberg spin couplings made simple: just one spin flip required.
Computational quantum chemistry for single Heisenberg spin couplings made simple: just one spin flip required.
复制标题
单海森堡自旋耦合的计算量子化学变得简单：只需要一次自旋翻转。
DOI：
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发表时间：
2014
影响因子：
4.4
通讯作者：
M. Head‐Gordon
中科院分区：
文献类型：
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作者：
N. Mayhall;M. Head‐Gordon
我们强调了一个简单的策略来计算磁耦合常数，J，为一个配合物包含两个多自由基中心。在系统遵循海森堡哈密顿物理学的假设下，J是从一个自旋翻转电子结构计算中得到的，其中只有一个电子被激发（并且自旋翻转），从最大Ŝz的单个参考M到M - 1流形，而不考虑自由基中心上未配对电子的数量2M。在包含2M轨道的活动空间图中，只需要一个β电子和一个α空穴。虽然这种观察非常简单，但将基本配置的数量从M的指数型减少到线性型提供了巨大的计算优势。这个（M, M - 1）策略用于评估J是一个明确的，自旋纯的，波函数理论对应于各种投影破缺对称密度泛函理论方案，同样给出了每个可能的自旋态的显式能量，从而能够评估性质。本文以五种不同数目的未配对电子的配合物为例说明了该方法，并讨论了自旋翻转方法进一步发展的一些意义。
We highlight a simple strategy for computing the magnetic coupling constants, J, for a complex containing two multiradical centers. On the assumption that the system follows Heisenberg Hamiltonian physics, J is obtained from a spin-flip electronic structure calculation where only a single electron is excited (and spin-flipped), from the single reference with maximum Ŝz, M, to the M - 1 manifold, regardless of the number of unpaired electrons, 2M, on the radical centers. In an active space picture involving 2M orbitals, only one β electron is required, together with only one α hole. While this observation is extremely simple, the reduction in the number of essential configurations from exponential in M to only linear provides dramatic computational benefits. This (M, M - 1) strategy for evaluating J is an unambiguous, spin-pure, wave function theory counterpart of the various projected broken symmetry density functional theory schemes, and likewise gives explicit energies for each possible spin-state that enable evaluation of properties. The approach is illustrated on five complexes with varying numbers of unpaired electrons, for which one spin-flip calculations are used to compute J. Some implications for further development of spin-flip methods are discussed.