Local paramagnetic term

Considering the nucleus (and, similarly, most nuclei other than H), the main contribution to the magnetic shielding constant is the so-called local paramagnetic term ... 

The relative nitrogen screening constants of pyridine, pyrazine, pyridazine, pyrimidine, 1,3,5-triazine and 1,2,4,5-tetrazine show a very good linear correlation with theoretical values of the local paramagnetic term calculated by the AEE approximation. (47) A similarly satisfactory... 

Pu being the charge density or occupancy of orbital i of atom A in the molecule. The second term, a%, a paramagnetic term representing a local correction for the molecular environment, involves the mixing of ground and excited electronic states. This term is extremely difficult to calculate and no exact expression has been found using many-electron theory. Karplus and Pople have represented Op as... 

X.CO.Y in terms of the Karplus and Pople theory for the local paramagnetic contribution 5p. If the following assumptions are made—... 

We now turn to the important paramagnetic term a. In the original Pople LCAO MO approximation the local paramagnetic shielding term for an atom A takes the form... 

Taking into account that relevant excitation energies are fairly constant, the paramagnetic term cXp, which represents the imbalance of charge, could be related to local symmetry. It has been established that an... 

Nakano and Nakatsuji et have calculated dia- and paramagnetic terms for [MnX(CO)s] (X = Hal, H, CN, Me), [Mn(CO)e]+, and [Mn04]". A qualitative agreement is found between the calculated paramagnetic diamagnetic terms are practically con-... 

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