So as far as getting to correct symmetries of interacting atomic orbitals for an MO diagram for triatomic molecules, I would employ the following method:
1. assign a point group to the molecule
2. assign x, y and z axis taking z as principal axis for a linear molecule
3. find the characters of REDUCIBLE REPRESENTATION for outer atoms using point groups (to give gamma)
4. reduce this to irreducible representation (using equation derived from group theory)
5. find AOs from central atom with same symmetry
6. match symmetries and create bonding, anti bonding, non bonding orbitals...
However, I am not sure how to change the procedure for a diatomic that obviously doesn't have a central atom-how do I get to the reducible representation of CO? I have got as far as assigning it to the point group C2v by symmetry reduction (instead of Cinfinityv, because you don't want an infinite number of operations in reducible representation)...now I am stuck!!!
Claims damages because he didn't get a first