自相互作用修正下Mn二聚体的密度泛函计算
Mn Dimer can be Described Accurately with Density Functional Calculations when Self-interaction Correction is Applied
摘要：
在密度泛函理论计算中，用广义梯度近似（GGA）得到了Mn二聚体的定性不正确的结果，而用局域密度和元GGA泛函得到了类似的结果.耦合被预测为铁磁而不是反铁磁，原子之间的键被预测为一个数量级太强，大约一个短的数量级。然而，应用于常用GGA能量泛函的显式自相互作用校正（SIC）提供了与实验数据和高水平多参考波函数计算的密切一致。这些结果表明，失败是由于强相关性，而是单电子自相互作用，这是必然引入的经典库仑和交换相关能量的估计时，只有总电子密度作为输入。修正后的泛函明确地依赖于轨道密度，因此，可以避免引入自库仑相互作用。误差的产生是由于过高估计了半局域交换关联泛函中的$d$ -电子自相互作用，导致少数自旋通道中的键合$d$ -态的过度稳定。由于自相互作用校正计算中的计算工作量以与常规半局部函数计算相同的方式与系统大小成比例，因此这种方法提供了一种计算Mn纳米团簇以及生物分子和扩展固体的性质的方法，其中存在Mn二聚体和较大的团簇，而多参考波函数计算只能应用于小系统。
英文摘要：
Qualitatively incorrect results are obtained for the Mn dimer in density functional theory calculations using the generalized gradient approximation (GGA) and similar results are obtained from local density and meta-GGA functionals. The coupling is predicted to be ferromagnetic rather than antiferromagnetic and the bond between the atoms is predicted to be an order of magnitude too strong and about an Ångstrøm too short. Explicit, self-interaction correction (SIC) applied to a commonly used GGA energy functional, however, provides close agreement with both experimental data and high-level, multi-reference wave function calculations. These results show that the failure is not due to strong correlation but rather the single electron self-interaction that is necessarily introduced in estimates of the classical Coulomb and exchange-correlation energy when only the total electron density is used as input. The corrected functional depends explicitly on the orbital densities and can, therefore, avoid the introduction of self-Coulomb interaction. The error arises because of over-stabilization of bonding $d$-states in the minority spin channel resulting from an overestimate of the $d$-electron self-interaction in the semi-local exchange-correlation functionals. Since the computational effort in the self-interaction corrected calculations scales with system size in the same way as for regular semi-local functional calculations, this approach provides a way to calculate properties of Mn nanoclusters as well as biomolecules and extended solids where Mn dimers and larger cluster are present, while multi-reference wave function calculations can only be applied to small systems.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
