  Charge transfer among individual atoms in a molecule is the key concept in
the modern electronic theory of chemical bonding. In this work, we defined an
atomic region between two atoms by Slater orbital exponents of valence
electrons and suggested a method for analytical calculation of charge
penetration between all atoms in a molecule. Computation of charge penetration
amount is self-consistently performed until each orbital exponent converges to
its certain values respectively. Charge penetration matrix was calculated for
ethylene and MgO, and bonding charge and its distribution were analyzed by
using the charge penetration matrix and the orbital exponents under the bonding
state. These results were compared with those by density function method and
showed that this method is a simple and direct method to obtain bonding charge
distribution of molecule from atomic orbital functions.
