Approximate Evaluation of V r

Among the more widely used approximate procedures for computing V(r) are those based upon multipole expansions. Such a representation can 

An important recent development comes from the recognition that an electronic density function written in terms of a gaussian basis set can be expressed as a finite multicenter expansion.(The centers are not limited to nuclei.) The resulting V(r), based on an expansion through the quadrupole terms, has been found to agree well with that obtained rigorously from the same p(r), with a very marked reduction in the computer time required.  

There has been a continuing interest, over a period of many years, in the idea of representing the electrostatic potentials of large chemical systems as a combination or superposition of contributions from their constituent 

---