The chemical reactivity of radical pairs is strongly influenced by the interactions of electronic and nuclear spins. A detailed understanding of these effects requires a quantum description of the spin dynamics that considers spin-dependent reaction rates, interactions with external magnetic fields, spin–spin interactions, and the loss of spin coherence caused by coupling to a fluctuating environment. Modeling real chemical and biochemical systems, which frequently involve radicals with multinuclear spin systems, poses a severe computational challenge. Here, we implement a method based on the stochastic Schrödinger equation in the software package MolSpin. Large electron–nuclear spin systems can be simulated efficiently, with asymmetric spin-selective recombination reactions, anisotropic hyperfine interactions, and nonzero exchange and dipolar couplings. Spin-relaxation can be modeled using the stochastic time-dependence of spin interactions determined by molecular dynamics and quantum chemical calculations or by allowing rate coefficients to be explicitly time-dependent. The flexibility afforded by this approach opens new avenues for exploring the effects of complex molecular motions on the spin dynamics of chemical transformations.

中文翻译：

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在 MolSpin 中使用随机薛定谔方程的自由基对自旋动力学


自由基对的化学反应性受电子和核自旋相互作用的强烈影响。要详细了解这些效应，需要对自旋动力学进行量子描述，该描述考虑了与自旋相关的反应速率、与外部磁场的相互作用、自旋-自旋相互作用以及由于耦合到波动环境而导致的自旋相干性损失。模拟真实的化学和生化系统，其中经常涉及具有多核自旋系统的自由基，这带来了严峻的计算挑战。在这里，我们实现了一种基于软件包 MolSpin 中的随机薛定谔方程的方法。通过不对称自旋选择性复合反应、各向异性超精细相互作用以及非零交换和偶极耦合，可以有效地模拟大型电子-核自旋系统。自旋弛豫可以使用由分子动力学和量子化学计算确定的自旋相互作用的随机时间依赖性来建模，或者允许速率系数显式地与时间相关。这种方法提供的灵活性为探索复杂分子运动对化学转变的自旋动力学的影响开辟了新的途径。