Manifestation of descent symmetry phenomena induced by pseudo Jahn–Teller interactions is reported for the P 4 dicationic tetrahedral structure and its As 4 and Sb 4 analogues. The symmetry descent phenomena in the dicationic tetrahedral structure for the series is caused by the pseudo Jahn–Teller effect (PJTE) where the unstable (high T d symmetry) configuration distorts to the equilibrium geometry with a lower, C 2 symmetry. State averaging six low-lying electronic states via CASSCF(8,8)/cc-pVTZ–(PP) computations determined the adiabatic potential energy surfaces along the distorting normal coordinate. The (E (I) + A 1 + E (II) ) ⊗ e for the M 4 2+ (M = P, As, Sb) series has been formulated accordingly. Subsequently, the coupling constants were estimated by fitting energies obtained from the PJTE equations. Moreover, to understand how removing or adding electrons affects the PJTE in the M 4 2+ series, electronic configurations were analysed for M 4 (0,2+,4+) analogues in which the M 4 (0,4+) are stable in their tetrahedral structure.

中文翻译：

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M42+ (M = P, As, Sb) 类似物四面体结构中下降对称现象的表现

对于 P 4 双阳离子四面体结构及其 As 4 和 Sb 4 类似物，报告了由伪 Jahn-Teller 相互作用引起的下降对称现象的表现。该系列的双阳离子四面体结构中的对称下降现象是由伪 Jahn-Teller 效应 (PJTE) 引起的，其中不稳定的（高 T d 对称性）配置扭曲到具有较低 C 2 对称性的平衡几何形状。通过 CASSCF(8,8)/cc-pVTZ–(PP) 计算对六个低位电子状态进行平均的状态确定了沿扭曲法向坐标的绝热势能面。M 4 2+ (M = P, As, Sb) 系列的 (E (I) + A 1 + E (II) ) ⊗ e 已相应地公式化。随后，通过拟合从 PJTE 方程获得的能量来估计耦合常数。而且，