EHMO Extended Hückel MO

ehmo ICON-EDiT is a semiempirical molecular orbital package for the study of molecular properties, including excited states ("EDiT"), and structure optimization ("GOP"). A solid state package "BICON-EDiT" is also available. Based on original work of the Roald Hoffmann group the present version with many additions and improvements has been developed by Gion Calzaferri, Bern, and his group. It can be downloaded from Calzaferri's homepage. Several packages for Windows-OS's and Unix(Linux) OS's are offered under GNU open source declaration. In addition an excellent tutorial "Manual.pdf", many worked examples, and most of the recent publications of the group, pertinent to EHMO, can be obtained for free.
instructions The inputform and runscript above is constantly developed. It presently allows to select and run "classical" extended Hückel calculations, charge-iteration on one, several or all atoms. Among Calzaferri's extensions the core-core repulsion energy term and three versions for the calculation of the off-diagonal Hij Hamilton matrix elements can be chosen interactively. Some of the properties calculated:
  • Overlap matrix
  • Energy levels
  • Molecular orbitals
  • Atomic net charges
  • 1-electron energies
  • core-core repulsion
  • Orbital population
The script calls Iconc.exe (2000) on Windows 9x, NT4, Windows2000, XP. The coordinates can be input from a graphical molecule builder (see information in RUNpcg), pasted into the inputfile manually or from another application. A successful run opens the output in Notepad.

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Iconform2000 the input and run script and several auxiliary files.
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