The stucture is perfectly tetrahedral. You should be able to build the molecule yourself, using the techniques described in earlier tutorials. One possible way:
Start ADFinput Build a tetrahedral metal complex using the Structures button (Metal Complexes>ML4 tetrahedral) Change the central atom into a Ni atom Select the ligands (use the pop-up menu Atom Popup → Select All XX atoms) Change them in CO ligands (again in the pop-up menu Atom Popup → Add Structures → Ligands → CO) Choose the 'Geometry Optimization' Preset Save and Run When the run has finished, click 'yes' to import the optimized coordinates Save
Your molecule should look something like this:
