Matsika Spiridoula, Yarkony David R
Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA.
J Am Chem Soc. 2003 Sep 3;125(35):10672-6. doi: 10.1021/ja036201v.
Using multireference configuration interaction expansions comprised of over 7 million configuration state functions, three-state conical intersections are reported for the closely spaced, spectroscopically observed (tilde)B(2A1), (tilde)C(2B1), and (tilde)D(2B2) states (in C(2v) symmetry) of the allyl radical. These conical intersections of states which were previously assigned as the 3,4,5(2)A states and are here reassigned as the 4,5,6(2)A states, are expected to be accessible using optical probes. This conclusion is obtained from the structure of the minimum energy point on the 4,5,6(2)A three-state conical intersection seam which is similar to the equilibrium structure of the ground (tilde)X(2A2) state and only 1.1 eV above the (tilde)D(2B2) state at its equilibrium geometry. The seam of three-state degeneracies joins two two-state seams of conical intersection, the 4,5(2)A and 5,6(2)A conical intersection seams. The energy of the minimum energy point on the 4,5(2)A two-state seam is only 0.15 eV above that of the (tilde)D(2B2) state at its equilibrium structure. Three-state intersections are also reported for the 3,4,5(2)A states.
利用由超过700万个组态态函数组成的多参考组态相互作用展开，报道了烯丙基自由基在C(2v)对称性下紧密间隔、光谱观测到的（tilde）B(2A1)、（tilde）C(2B1)和（tilde）D(2B2)态的三态锥形交叉。这些以前被指定为3,4,5(2)A态而现在重新指定为4,5,6(2)A态的态的锥形交叉，有望通过光学探针实现。这一结论是从4,5,6(2)A三态锥形交叉缝上的最低能量点的结构得出的，该结构类似于基态（tilde）X(2A2)态的平衡结构，在其平衡几何结构下仅比（tilde）D(2B2)态高1.1 eV。三态简并缝连接了两个双态锥形交叉缝，即4,5(2)A和5,6(2)A锥形交叉缝。在其平衡结构下，4,5(2)A双态缝上的最低能量点的能量仅比（tilde）D(2B2)态高0.15 eV。还报道了3,4,5(2)A态的三态交叉。
