Theoretica chimica acta

, Volume 42, Issue 1, pp 33–45 | Cite as

Population analysis based on occupation numbers of modified atomic orbitals (MAOs)

  • Rolf Heinzmann
  • Reinhart Ahlrichs
Original Investigations


A new interpretational scheme is proposed for the analysis of molecular wavefunctions. Starting from the molecular density operator we first construct a minimal set of MAOs from the requirement that the MOs can be represented as closely as possible by the MAOs. We then use the MAOs to compute atomic occupation numbers N and shared electron numbers σ. The molecular density is then discussed in terms of N and σ. This approach has the following advantages: 1) it is generally applicable, 2) the quantities N and σ are virtually basis set independent, 3) the quantities N and σ fulfil the intuitively expected boundary conditions, 4) the simultaneous consideration of N and σ allows for a more reliable description of chemical bonding than consideration of atomic charges only.

Key words

Population analysis Occupation numbers Modified AOs 


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Copyright information

© Springer-Verlag 1976

Authors and Affiliations

  • Rolf Heinzmann
    • 1
  • Reinhart Ahlrichs
    • 1
  1. 1.Institut für Physikalische Chemie und Elektrochemie der Universität KarlsruheKarlsruheFederal Republic of Germany

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