Rantaharju Jyrki, Mareš Jiří, Vaara Juha
NMR Research Group, Department of Physics, University of Oulu, P.O. Box 3000, Oulu, FIN-90014, Finland.
J Chem Phys. 2014 Jul 7;141(1):014109. doi: 10.1063/1.4885050.
The ability to quantitatively predict and analyze the rate of electron spin relaxation of open-shell systems is important for electron paramagnetic resonance and paramagnetic nuclear magnetic resonance spectroscopies. We present a combined molecular dynamics (MD), quantum chemistry (QC), and spin dynamics simulation method for calculating such spin relaxation rates. The method is based on the sampling of a MD trajectory by QC calculations, to produce instantaneous parameters of the spin Hamiltonian used, in turn, to numerically solve the Liouville-von Neumann equation for the time evolution of the spin density matrix. We demonstrate the approach by simulating the relaxation of electron spin in an aqueous solution of Ni(2+) ion. The spin-lattice (T1) and spin-spin (T2) relaxation rates are extracted directly from the simulations of the time dependence of the longitudinal and transverse magnetization, respectively. Good agreement with the available, indirectly obtained experimental data is obtained by our method.
对于电子顺磁共振和顺磁核磁共振光谱学而言，定量预测和分析开壳层体系中电子自旋弛豫速率的能力至关重要。我们提出了一种结合分子动力学（MD）、量子化学（QC）和自旋动力学的模拟方法来计算此类自旋弛豫速率。该方法基于通过QC计算对MD轨迹进行采样，以生成所使用的自旋哈密顿量的瞬时参数，进而数值求解自旋密度矩阵时间演化的刘维尔 - 冯·诺依曼方程。我们通过模拟Ni(2+)离子水溶液中电子自旋的弛豫来演示该方法。自旋 - 晶格（T1）和自旋 - 自旋（T2）弛豫速率分别直接从纵向和横向磁化强度时间依赖性的模拟中提取。我们的方法与现有的间接获得的实验数据取得了良好的一致性。
