Kimball.exe

This is a program developed by Dr. Silvan Perego during his diploma thesis with me (University of Bern, 1989). It is an approach to a parametrized quantitative "Kimball"-Model, partially based on numerous earlier programs (by ES and students) concerning several molecular classes from hydrocarbons to very polar species. The K-Model is a simple Density Functional procedure (a forerunner akin to the X-alpha method, published 1957 by G.E. Kimball, then Prof. of Physical Chemistry, Columbia University, NY, and G.F. Neumark in J.Chem.Phys.26(1957)1285). It requires parametrization because it does not obey the Variation Principle (as often true for DFT methods, if the electron density is not "v-representable", see R.G. Parr & W. Yang, Density-Functional Theory of Atoms and Molecules, Oxford Univ. Press, Oxford, 1989, (ISBN 0-19-504279-4), p. 52 ff.).
The equivalence of Kimball's model with Slater-type-orbitals is shown in this derivation.
A small set of parameters is sufficient to obtain the general accuracy of force-field methods in molecular energy and structure, but Kimball.exe is much faster. In comparison to ab initio ESS-methods it produces energies and structures near RHF/6-31g model chemistries as computed with Gaussian98 or Gamess, again much faster. At this moment, Kimball.exe is restricted to molecules and ions with up to 50 atoms from H to F and singlet groundstates. More specialized programs which treat molecules and crystals including atoms from H to Cr and higher multiplet states have been tested successfully, however.

Last updated March 28, 2000
This page by ES.