Neglect of Differential Overlap Schemes

The earliest complete neglect of differential overlap method was introduced by Pople and his collaborators in 1965. - This scheme w as parameterized directly on minimum basis set ab initio calculations.  

To create a successful scheme, Pople introduced, in addition to the theoretical considerations discussed above, the following assumptions  

All two-center, two-electron integrals were set to the integral over s symmetry orbitals, a requirement for rotational invariance discussed above  

The off-diagonal, one-electron or resonance integrals were set proportional to the overlap integral. 

Here p,( is a parameter that depends only on the nature of atom A. 

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The intermediate neglect of differential overlap scheme developed by Rdsch, Zemer, and co-workers for the ground state (INDO/0) and the spectroscopy of excited states (INDO/S) allows an even larger reduction of the computational effort. The method appears to give rather accurate results for the lanthanide series however, owing to missing experimental data for the parametrization the performance for the actinide series appears to be less satisfactory. 

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