37.10.5 Symmetry relations between orbitals

In general, for a VB wavefunction to be symmetry-pure, the orbitals must form a representation (not necessarily irreducible) of the symmetry group. Relations between orbitals under the symmetry operations defined by SYMELM may be specified according to:

ORBREL,i$_1$, i$_2$, label1, label2,...;

Orbital $i_1$ is related to orbital $i_2$ by the sequence of operations defined by the label specifications (defined previously using SYMELM). The operators operate right to left. Note that $i_1$ and $i_2$ may coincide. Only the minimum number of relations required to define all the orbitals should be provided; an error exit will occur if redundant ORBREL specifications are found.