The header for each orbital includes the orbital symmetry, the label "O" for occupiedor "V" for virtual orbitals, and the orbital energies in atomic units. In the next section of output, the orbital coefficients are given first for the five highest occupiedmolecular orbitals. For open shell systems the energies of the alpha electrons are given first, followed by the energies of the beta orbitals: Following this information, the orbital energies of all orbitals of the system are given. 8 and belongs to the B 2 irreducible representation (antisymmetric with respect to the principal C 2 axis). In thisparticular example, the highest occupied molecular orbital (HOMO) is orbital No. The output starts with a listing of the orbital symmetries of all orbitals of the system. The orbital coefficients aregiven with respect to the molecule in its "Standard orientation" given at the beginning of the output file.The system is oriented such that the principal axis of the systems runs along the z-axis andthat all atoms of the system are located in the yz-plane: There are only four virtual orbitals and only those are printed. In the followingexample of the HF/STO-3G orbitals of formaldehyde (CH 2O, C 2v point group): This is, of course, onlypossible if there actually ARE at least five occupied and five virtual orbitals. Using this choice, information on the five highest occupied and the lowest five uncoccupied (virtual) orbitals are printed. Selected information on the actual orbitals is obtainedusing pop=regular. How much information on molecular orbitals is written to the Gaussian output file depends on the value of the Population or pop keyword.If no particular value is given, only the orbital energies (in atomic units) are printed. Orbitals Information on Molecular Orbitals in the Gaussian output file