Lefrancois Daniel, Wormit Michael, Dreuw Andreas
Interdisciplinary Center for Scientific Computing, Ruprecht-Karls University, Im Neuenheimer Feld 368, 69120 Heidelberg, Germany.
J Chem Phys. 2015 Sep 28;143(12):124107. doi: 10.1063/1.4931653.
For the investigation of molecular systems with electronic ground states exhibiting multi-reference character, a spin-flip (SF) version of the algebraic diagrammatic construction (ADC) scheme for the polarization propagator up to third order perturbation theory (SF-ADC(3)) is derived via the intermediate state representation and implemented into our existing ADC computer program adcman. The accuracy of these new SF-ADC(n) approaches is tested on typical situations, in which the ground state acquires multi-reference character, like bond breaking of H2 and HF, the torsional motion of ethylene, and the excited states of rectangular and square-planar cyclobutadiene. Overall, the results of SF-ADC(n) reveal an accurate description of these systems in comparison with standard multi-reference methods. Thus, the spin-flip versions of ADC are easy-to-use methods for the calculation of "few-reference" systems, which possess a stable single-reference triplet ground state.
为了研究具有表现出多参考特征的电子基态的分子体系，通过中间态表示法推导了极化传播子的代数图示构建（ADC）方案的自旋翻转（SF）版本，直至三阶微扰理论（SF-ADC(3)），并将其实现到我们现有的ADC计算机程序adcman中。在典型情况下测试了这些新的SF-ADC(n)方法的准确性，其中基态具有多参考特征，如H₂和HF的键断裂、乙烯的扭转运动以及矩形和平面正方形环丁二烯的激发态。总体而言，与标准多参考方法相比，SF-ADC(n)的结果揭示了对这些体系的准确描述。因此，ADC的自旋翻转版本是用于计算具有稳定单参考三重态基态的“少参考”体系的易用方法。
