This method keyword requests an extended Huckel calculation [Hoffmann63, Hoffmann64, Hoffmann64a, Hoffmann64b, Hoffmann66]. ExtendedHuckel is a synonym for this keyword. No basis set keyword should be specified.
Hoffmann
Requests an Extended Huckel calculation using the default parameter set from the Huckel group.
Muller
Requests an Extended Huckel calculation using parameters collected by Edgar Muller.
Guess
Requests an Extended Huckel calculation using the modified parameters used for Guess=Huckel [Pyykko81, Pyykko84, Fitzpatrick86].
Energies, “analytic” gradients and numerical frequencies.
The energy appears in the output file as follows (followed by the x, y, and z components of the dipole moment):
Huckel eigenvalues -- -1.245 -0.637 -0.558 -0.544 -0.043 0.352 Energy= -5.968836513622 NIter= 0. Dipole moment= 0.000000 0.000000 0.000000
The energy is as defined by this semi-empirical model. Note that energy differences computed from the values in semi-empirical calculations are in Hartrees and may be compared directly with energy differences computed from jobs using other methods.
Last update: 23 April 2013