HMO allows you to focus on the results of the Hückel calculations, rather than getting bogged down in entering data.

To use HMO you draw the structure you want to investigate using the simple built-in drawing tools. The program then analyzes the structure, separates the pi electron network, performs the Hückel calculations and displays the results, including total pi energy, pi electrons, LUMO and HOMO energy and orbitals, charge densities and pi bond orders. Data may be printed.
.

"...most useful for research groups that are looking for something... more sophisticated than the 'back of the envelope' that they might have been using for Hückel calculations on organic systemsHMO is easy to learn and inexpensive and can be run on platforms available on most campuses and in most research groups."

JACS - Vol 114, No. 22
(Review of Version 2.0)
.

Version 3.0 offers:

• Drawing tools in an easily accessed palette.

• Givens-Householder matrix diagonalization with a four- fold increase in computational speed.

• Inclusion of the iterative Omega technique for more advanced computation.

• Maximum pi-system: 100 orbitals.

• Structures may have as many as 128 atoms.

• Heteroatoms B, O, N, F, I, Cl, and Br are fully supported, but only P-orbitals are considered for sulfur.

• The default parameter set is taken from Molecular Orbital Theory for Organic Chemists by Streitweiser (John Wiley & Sons, 1961) with Auxiliary Inductive Parameters included.

• A zero-order set is built into the program.