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:
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.