Step 3. Occupations

Now we will remove one electron from a selected orbital (by symmetry) using ADFinput again.

Open your benzene calculation in ADFinput
Open the spin and occupation panel

In the Spin and Occupation panel you see which orbitals are available (by symmetry, and spin if the current set up is unrestricted). The numbers are the occupations. Next to the ADFinput window ADFlevels will also have opened, and is showing a level diagram of your current molecule. This helps you to select the proper occupation.

The level diagram is based on the existing result file (.t21) found. If none, ADFinput will suggest to do a guess-calculation: a hopefully fast calculation using an inaccurate integration grid, and stopping after a few SCF cycles. The level diagram shown in that case will not be accurate obviously but will still be helpful in selecting the proper occupation.

Now, just as an example, we make a hole in the 3E2.g orbital. Note that this is NOT the HOMO.

Change the 4.0 to 3.0 in the 3 E2.g column (the third row)

Close the guess adflevels
Run
When the run is complete, open ADFlevels using the Levels command from the SCM menu
In the ADFlevels window, use the View→Labels→Show command
Zoom in to the region of interest (for example using your mouse wheel)

In the levels diagram you will observe that the HOMO (the 1E1.g) is completely filled, while the orbital below it has a hole. You can easily see this by the color. Note that we have performed a restricted calculation, so in effect the hole is averaged over the E orbitals.