CNDO/2

CNDO is the short cut for Complete Neglect of Differential Overlap. It is both 1) a method for learning key facts about molecular orbitals as well as 2) the name of a particular set of computer programs. CNDO is based on quantum chemistry. It is one of the first semi-empirical quantum chemistry methods. It uses two approximations:
core approximation - only the outer valence electrons are explicitly included.
zero-differential overlap

CNDO builds a mathematical model of a molecule. CNDO starts with the position of the positively charged nuclei of the atoms and the negatively charged electron clouds surrounding them.  Quantum chemistry tells the model the probability distribution of electron locations based on atomic orbitals.  From this information, CNDO computes data about the resulting molecular orbitals.

CNDO/2 is the main version of CNDO. John Pople and coworkers first wrote CNDO/2.J. Pople and D. Beveridge, Approximate Molecular Orbital Theory, McGraw-Hill, 1970.J.A. Pople, D.P. Santry and G.A. Segal, Journal of Chemical Physics, 43, S129, (1965)J.A. Pople and G.A. Segal, Journal of Chemical Physics, 43, S136, (1965)J. Pople and G.A. Segal, Journal of Chemical Physics, 44, 3289 (1966)D.P. Santry and G.A. Segal, Journal of Chemical Physics, 47, 158 (1967)

References

Other websites
CNDO/2 Calculation (Pirika)
Molecular Modeling for Educators 
Density Functional Modelling of Point Defects in Semiconductors 

Category:Semiempirical quantum chemistry methods