Do a single-point Hartree-Fock calculation (HF keyword) using the def2-TZVP basis set on some atoms and molecules. The geometries that you use for the molecules can be either previous geometries that you have optimized, geometries that you optimize first yourself in a separate job or perhaps a geometry created using the experimental bond lengths.
Use the following inputfile. The extra keyword writes orbital-output to the outputfile so that Chemcraft can visualize the orbitals later.
! HF def2-TZVP Normalprint
%output
Print[ P_Basis ] 2
Print[ P_MOs ] 1
end
Once the calculations are done, copy the outputfile to your computer and open in Chemcraft. Then go to the menubar to Tools -> Orbitals -> Render Molecular orbitals. From the list of orbitals, check the ones you are interested in and render them.
You might have to play around a bit with the contour value, 0.05 is usually a good number. If you go to "Style..." you can choose "Lines" which is a convenient way of showing the orbital isosurfaces.
1. Hydrogen atom.
Explore the groundstate wavefunction and excited state wavefunctions of the hydrogen atom. You should be able to find s and p-functions.
2. H2 molecule
Find the bonding and antibonding molecular orbitals of this molecule. What is the bond order of this molecule according to your analysis?
3. O2 molecule.
Find the bonding and antibonding molecular orbitals of this molecule. Describe the orbitals that you see, look at the occupation numbers. Compare to a Lewis structure. What is the bond order of this molecule according to your analysis?
Comment: There has been some disagreement on the relative order of sigma vs. pi orbitals for O2. Experimental photoelectron spectra suggest the orbital ordering that you will see in most MO diagrams for O2. Hartree-Fock calculations predict a slightly different ordering. While comparing orbital energy levels (orbitals are not observable!) and experimental spectra is slightly problematic, it should be noted that a B3LYP DFT calculation gives an ordering more in line with the experimentally derived MO diagram and the typical O2 MO diagram seen in textbooks.
4. N2 molecule
Find the bonding and antibonding orbitals of this molecule. Describe the orbitals that you see, look at the occupation numbers. Compare to a Lewis structure. What is the bond order of this molecule according to your analysis?
5. HF molecule
Find the bonding, antibonding and non-bonding orbitals of this molecule. Describe the orbitals that you see, look at the occupation numbers. Compare to a Lewis structure. What is the bond order of this molecule according to your analysis?
This molecule is heteronuclear. Does this affect the shape of the molecular orbitals, which ones? Why?
The report should include figures of relevant orbitals for the molecules and a qualitative description of what they are.
Note: One of the molecules in this exercise is not a regular singlet (spin,S, is not 0). You will calculate a wrong excited state of the molecule if you don't realize this.