Department of Physical Chemistry, University of Geneva, 30q. E. Ansermet, 1211 Genève, Switzerland.
Phys Chem Chem Phys. 2009 Dec 14;11(46):10964-72. doi: 10.1039/b912607d. Epub 2009 Oct 14.
Multiconfigurational second-order perturbation theory based on either a complete active space reference wave function (CASSCF/CASPT2) or a restricted active space reference wave function (RASSCF/RASPT2) has been applied to compute one-electron ionization potentials and vertical electronic energy differences of oligomers of length n formed from ethylene (n = 1-10), acetylene (n = 1-5), and phenylene (n = 1-3) subunits. The RASSCF/RASPT2 approach offers an accuracy similar to CASSCF/CASPT2 at significantly reduced computational expense (both methods show good agreement with experimental data where available). It is shown that RASPT2 extends the range of CASPT2-like approaches by permitting the use of larger active spaces.
多组态二级微扰理论基于完全活性空间参考波函数（CASSCF/CASPT2）或受限活性空间参考波函数（RASSCF/RASPT2），已被应用于计算由乙烯（n = 1-10）、乙炔（n = 1-5）和亚苯基（n = 1-3）亚基组成的长度为 n 的低聚物的单电子电离势和垂直电子能差。RASSCF/RASPT2 方法以显著降低的计算成本提供了与 CASSCF/CASPT2 相似的精度（两种方法与现有实验数据吻合良好）。结果表明，RASPT2 通过允许使用更大的活性空间扩展了类似于 CASPT2 的方法的范围。
