Blancafort Lluís, Voityuk Alexander A
Institut de Química Computational, Departament de Química, Universitat de Girona, 17071 Girona, Spain.
J Phys Chem A. 2007 May 31;111(21):4714-9. doi: 10.1021/jp067886z. Epub 2007 May 8.
Calculations using the complete active space self-consistent field (CASSCF) and complete active space second-order perturbation (CASPT2) methods, and the multistate formulation of CASPT2 (MS-CASPT2), are performed for the ground and excited states of radical anions consisting of two pi-stacked nucleobases. The electronic couplings for excess electron transfer (EET) in the pi-stacks are estimated by using the generalized Mulliken-Hush approach. We compare results obtained within the different methods with data derived using Koopmans' theorem approximation at the Hartree-Fock level. The results suggest that although the one-electron scheme cannot be applied to calculate electron affinities of nucleobases, it provides reasonable estimates for EET energies. The electronic couplings calculated with KTA lie between the CASPT2 and the MS-CASPT2 based values in almost all cases.
使用完全活性空间自洽场（CASSCF）和完全活性空间二阶微扰（CASPT2）方法以及CASPT2的多态公式（MS-CASPT2），对由两个π堆积核碱基组成的自由基阴离子的基态和激发态进行了计算。通过使用广义穆利肯-赫什方法估计π堆积中多余电子转移（EET）的电子耦合。我们将不同方法得到的结果与在哈特里-福克水平上使用库普曼定理近似得出的数据进行比较。结果表明，虽然单电子方案不能用于计算核碱基的电子亲和能，但它为EET能量提供了合理的估计。在几乎所有情况下，用KTA计算的电子耦合值介于基于CASPT2和MS-CASPT2的值之间。
