SELF-CONSISTENT PERTURBATION-THEORY OF DIAMAGNETISM .1. GAUGE-INVARIANT LCAO METHOD FOR NMR CHEMICAL-SHIFTS
SELF-CONSISTENT PERTURBATION-THEORY OF DIAMAGNETISM .1. GAUGE-INVARIANT LCAO METHOD FOR NMR CHEMICAL-SHIFTS
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DOI：
10.1080/00268977400100711
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发表时间：
1974-01-01
影响因子：
1.7
通讯作者：
DITCHFIELD, R
中科院分区：
文献类型：
--
作者：
DITCHFIELD, R
本文发展了用于核磁屏蔽的从头算规范不变分子轨道理论。分子轨道被写成规范不变原子轨道的线性组合，在均匀外磁场存在下的波函数由自洽场微扰理论确定。最后的磁屏蔽结果被分解成可以与电子结构的各种特征相关的贡献。计算的磁屏蔽常数使用三套原子轨道，所有这些都被视为压缩高斯型函数。前两个集合是最小的，第三个稍微扩展。所有三个层次的理论都很好地描述了第一行屏蔽和氢原子。在扩展水平上计算的碳和氢化学位移与实验值非常吻合。
Anab initiogauge-invariant molecular orbital theory is developed for nuclear magnetic shielding. The molecular orbitals are written as linear combinations of gauge-invariant atomic orbitals, the wavefunctions in the presence of a uniform external magnetic field being determined by self-consistent field perturbation theory. The final magnetic shielding result is broken up into contributions which can be related to various features of electronic structure. Calculated magnetic shielding constants are presented using three sets of atomic orbitals, all of which are taken as contracted gaussian-type functions. The first two sets are minimal and the third is slightly extended. All three levels of theory give good descriptions of shielding at first row and hydrogen atoms. Carbon and hydrogen chemical shifts calculated at the extended level are in excellent agreement with experimental values.