CNDO/2



CNDO is the abbreviation for Complete Neglect of Differential Overlap. Although CNDO is based on quantum chemistry, it is more specifically 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/2 is the main version of CNDO. The method was first introduced by John Pople and coworkers. [1] [2] [3] [4] [5]

Background

An earlier method was spectroscopy.

Methodology

Quantum mechanics provides equations based on the chemical bonds but instead uses knowledge about quantum wavefunctions.

CNDO can be used for both closed shell molecules, where the electrons are fully paired in molecular orbitals and open shell molecules, which are radicals with unpaired electrons.

CNDO is considered to yield good results about lowest unoccupied molecular orbital are reported from the closed shell approach.

See also

References

  1. ^ J. Pople and D. Beveridge, Approximate Molecular Orbital Theory, McGraw-Hill, 1970.
  2. ^ J. A. Pople, D. P. Santry and G. A. Segal, Journal of Chemical Physics, 43, S129, (1965)
  3. ^ J. A. Pople and G. A. Segal, Journal of Chemical Physics, 43, S136, (1965)
  4. ^ J. Pople and G.A. Segal, Journal of Chemical Physics, 44, 3289 (1966)
  5. ^ D.P. Santry and G.A. Segal, Journal of Chemical Physics, 47, 158 (1967)
 
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