Rinkevicius Zilvinas, de Almeida Katia Julia, Vahtras Olav
Department of Theoretical Chemistry, School of Biotechnology, The Royal Institute of Technology, SE-10691 Stockholm, Sweden.
J Chem Phys. 2008 Aug 14;129(6):064109. doi: 10.1063/1.2964102.
The density functional restricted-unrestricted approach for treatments of spin polarization effects in molecular properties using spin restricted Kohn-Sham theory has been extended from linear to nonlinear properties. It is shown that the spin polarization contribution to a nonlinear property has the form of a quadratic response function that includes the zero-order Kohn-Sham operator, in analogy to the lower order case where the spin polarization correction to an expectation value has the form of a linear response function. The developed approach is used to formulate new schemes for computation of electronic g-tensors and hyperfine coupling constants, which include spin polarization effects within the framework of spin restricted Kohn-Sham theory. The proposed computational schemes are in the present work employed to study the spin polarization effects on electron paramagnetic resonance spin Hamiltonian parameters of square planar copper complexes. The obtained results indicate that spin polarization gives rise to sizable contributions to the hyperfine coupling tensor of copper in all investigated complexes, while the electronic g-tensors of these complexes are only marginally affected by spin polarization and other factors, such as choice of exchange-correlation functional or molecular structures, will have more pronounced impact on the accuracy of the results.
利用自旋受限的科恩-沙姆理论处理分子性质中自旋极化效应的密度泛函受限-非受限方法已从线性性质扩展到非线性性质。结果表明，对非线性性质的自旋极化贡献具有二次响应函数的形式，其中包括零阶科恩-沙姆算符，这与期望值的自旋极化校正具有线性响应函数形式的低阶情况类似。所开发的方法用于制定计算电子g张量和超精细耦合常数的新方案，这些方案在自旋受限的科恩-沙姆理论框架内包含自旋极化效应。在本工作中，所提出的计算方案用于研究自旋极化对平面正方形铜配合物的电子顺磁共振自旋哈密顿参数的影响。所得结果表明，在所有研究的配合物中，自旋极化对铜的超精细耦合张量有相当大的贡献，而这些配合物的电子g张量仅受到自旋极化的轻微影响，其他因素，如交换-相关泛函的选择或分子结构，将对结果的准确性产生更显著的影响。
