3.5 Additional Input Sections

3.5.8 User-Defined Occupied Guess Orbitals ($occupied and

It is sometimes useful for the occupied guess orbitals to be different from the lowest Nα (or Nα+Nβ) orbitals. Q-Chem allows the occupied guess orbitals to be defined using the $occupied keyword. Using the $occupied input section, the user can choose which orbitals (by number) to occupy by specifying the α-spin orbitals on the first line of the $occupied section and the β-spin orbitals on the second line. For large molecules where only a few occupied virtual promotions are desired, it is simpler to use the $swap_occupied_virtual input section. Details can be found in Section 4.4.4.