University of Belgrade, Faculty of Physical Chemistry, Studentski trg 12, P.O. Box 47, PAC 105305, 11158 Belgrade, Serbia.
J Chem Phys. 2011 Jul 14;135(2):024314. doi: 10.1063/1.3608913.
The aim of the present study is to predict by means of ab initio calculations the vibronic and spin-orbit structure in the X (2)Π(u) electronic state of NC(4)N(+) and to elucidate some details in an observed laser-induced fluorescence spectrum of this species, particularly those interpreted in terms of the bending overtones and the spin-orbit splitting. The ground electronic state of NC(4)N(+) was investigated by density functional (B3LYP) and complete active space self-consistent field-multi-reference configuration interaction (CASSCF-MRCI) methods. The bending vibrational frequencies ω(T1) = 558 cm(-1), ω(T2) = 266 cm(-1), ω(C1) = 459 cm(-1), and ω(C2) = 113 cm(-1) were obtained. The spin-orbit coupling constant was calculated using state-average CASSCF wave functions in the framework of the MRCI method, and the value of A(SO) = -44 cm(-1) was determined. This quantity and the data for the bending frequencies and Renner parameters were employed for handling a combined effect of the vibronic and spin-orbit coupling, according to a model developed in our earlier studies.
本研究的目的是通过从头计算预测 NC(4)N(+)的 X(2)Π(u)电子态的振子和自旋轨道结构，并阐明该物种观察到的激光诱导荧光光谱中的一些细节，特别是那些用弯曲泛频和自旋轨道分裂来解释的细节。NC(4)N(+)的基态电子态通过密度泛函（B3LYP）和完全活性空间自洽场多参考组态相互作用（CASSCF-MRCI）方法进行了研究。弯曲振动频率 ω(T1) = 558 cm(-1)、ω(T2) = 266 cm(-1)、ω(C1) = 459 cm(-1) 和 ω(C2) = 113 cm(-1) 被获得。自旋轨道耦合常数是在 MRCI 方法的框架中使用状态平均 CASSCF 波函数计算的，确定了 A(SO) = -44 cm(-1) 的值。根据我们之前研究中开发的模型，将这个量和弯曲频率以及 Renner 参数的数据用于处理振子和自旋轨道耦合的组合效应。
