Aman Ken, Westlund Per-Olof
Department of Chemistry, Biophysical Chemistry, Umeå University, S-901 87, Umeå, Sweden.
Phys Chem Chem Phys. 2007 Feb 14;9(6):691-700. doi: 10.1039/b614821b. Epub 2006 Dec 22.
Direct calculation of electron spin relaxation and EPR lineshapes, based on Brownian dynamics simulation techniques and the stochastic Liouville equation approach (SLE-L) [Mol. Phys., 2004, 102, 1085-1093], is here generalized to high spin systems with spin quantum number S = 3/2, 2, 5/2, 3 and 7/2. A direct calculation method is demonstrated for electron spin-spin and spin-lattice relaxation, S-, X- and Q-band EPR-lineshapes and paramagnetic enhanced water proton T(1)- NMRD profiles. The main relaxation mechanism for the electron spin system is a stochastic second rank zero field splitting (ZFS). Brownian dynamics simulation techniques are used in describing a fluctuating ZFS interaction which comprises two parts namely the "permanent" part which is modulated by isotropic reorientation diffusion, and the transient part which is modulated by fast local distortion, which is also modelled by the isotropic rotation diffusion model. The SLE-L approach present is applicable both in the perturbation (Redfield) regime as well as outside the perturbation regime, in the so called slow motion regime.
基于布朗动力学模拟技术和随机刘维尔方程方法（SLE-L）[《分子物理学》，2004年，第102卷，第1085 - 1093页]对电子自旋弛豫和电子顺磁共振（EPR）线形进行的直接计算，在此被推广到自旋量子数S = 3/2、2、5/2、3和7/2的高自旋体系。展示了一种用于电子自旋 - 自旋和自旋 - 晶格弛豫、S波段、X波段和Q波段EPR线形以及顺磁增强水质子T(1) - 核磁共振扩散轮廓（NMRD）的直接计算方法。电子自旋系统的主要弛豫机制是随机二阶零场分裂（ZFS）。布朗动力学模拟技术用于描述波动的ZFS相互作用，它包括两部分，即由各向同性重取向扩散调制的“永久”部分，以及由快速局部畸变调制的瞬态部分，后者也由各向同性旋转扩散模型进行模拟。所提出的SLE-L方法在微扰（雷德菲尔德）区域以及微扰区域之外的所谓慢运动区域均适用。
