full form of CNDO

(CNDO), in which all integrals are set to zero unless A and B
are the same orbitals centred on the same nucleus, and likewise for C and D. The surviving
integrals are then adjusted until the energy levels are in good agreement with
experiment. The more recent semi-empirical methods make less draconian decisions
about which integrals are to be ignored, but they are all descendants of the early
CNDO technique. These procedures are now readily available in commercial software
packages and can be used with very little detailed knowledge of their mode of calculation.
The packages also have sophisticated graphical output procedures, which enable
one to analyse the shapes of orbitals and the distribution of electric charge in
molecules. The latter is important when assessing, for instance, the likelihood that a
given molecule will bind to an active site in an enzyme.