The unexpected abundance of HNO in the photodecomposition of the radical 2-nitrosooxy ethyl (CH₂CH₂ONO) is investigated through calculations of the potential energy surface by the anti-Hermitian contracted Schrödinger equation (ACSE) method, which directly generates the 2-electron reduced density matrix. The ACSE, which is able to balance single-reference (dynamic) and multi-reference (static) correlation effects, reveals some subtle correlation effects along the intrinsic reaction coordinate (IRC) en route to NO + oxirane, an IRC which offers a potential bifurcation to the HNO + vinoxy product channel. These effects were not fully captured by either single-reference techniques, such as coupled cluster, or multi-reference techniques, such as second-order multi-reference perturbation theory. These correlation effects reveal small to moderate energy changes in key transition states, which have implications for the reaction mechanism as related to the production of HNO.

中文翻译：

---

使用降低密度矩阵技术来捕获能量分布中的静态和动态相关性，以分解CH2CH2ONO自由基并支持非IRC途径

2-亚硝基氧基乙基（CH ₂ CH ₂通过使用反赫耳特收缩Schrödinger方程（ACSE）方法计算势能面来研究ONO），该方法直接生成2电子还原密度矩阵。ACSE能够平衡单参考（动态）和多参考（静态）的相关效应，揭示了沿本征反应坐标（IRC）到达NO +环氧乙烷时的一些微妙的相关效应，这种IRC具有潜在的分叉到HNO +乙烯基产物通道。这些影响不能通过单参考技术（例如耦合簇）或多参考技术（例如二阶多参考摄动理论）完全捕获。这些相关效应揭示了关键过渡状态中能量的小到中等变化，