There are four important models for describing the diamagnetic anisotropy of aromatic ring systems[1]. There are detailed considerations of the equations based on these models in the reviews available till now[2]. Without mentioning much of the details of the methods for obtaining these equations it can be pointed out at the outset that the resulting equation for the proton shieldings (chemical shifts) are for the isotropic values and depend on the anisotropy of the diamagnetic susceptibility of the aromatic ring. Hence there can be the ring current susceptibility only as the component perpendicular to the plane of the aromatic ring.

For the Biomolecular structure determination, NMR Chemical shifts induced by the Aromatic Ring Current effects become important parameters in conjunction with the X-ray methods. It becomes necessary hence, to be able to calculate this aromatic ring cuureent effect contributions to verify the structural parameters. The equations prevailing at present are all for the calculation of isotropic chemical shift values and the different variations of this equations are to improve for the way the induced magnetic moment localized or distributed in the molecular system particularly the aromatic delocalisation of the elctronic charge cloud, the ardius of the aromatic ring in comparison to the distances at which its influence is calculated. The effort has been to improve the validity of the point-dipole approximation.

Eventhough the NMR methods have been very effective in this context, there have been several inadequacies and hence the reliability could not be improved to the required degree. Part of this predicament could be discerned as due to the inherent ?averaging out? while deriving the equations for the isotropic shifts. With the experiences in handling the Full tensor Form Shielding tensor Calculations, it is being pointed out in this presentation that the explicit calculation of shielding tensor for the context followed by the necessary processing of the set of tensors with averaging and merging appropriately, the NMR methods could become an inherently informative tool for the structure determination.

An elementary calculation of the NMR isotropic chemical shift in the vicinity of the benzene molecule has been illustrated in these posters which is basically a calculation of the relevant Shielding tensors and then obtain the trace of the tensors for comparison with the calculated results available till now using the equations for the isotropic shifts.