19.7.2 Ordering using domains (SORT)

SORT,[THRCHCHG=charge][THREIG=eps],GROUP=igrp],[REVERT],centrelist

This directive only works for Pipek-Mezey localization. The orbitals are ordered according to domains and the given centrelist. The contributions of the centres to domains are determined by Löwdin charges. Only centres with charges greater than THRCHCHG (default 0.4) are included in these domains. The orbitals are reordered according to the following criteria:

1.)

The primary centre in a domain is the one with largest charge, the secondary centre the one with the next largest charge. Orbitals are reordered separately within each localization group. First all orbitals are sorted so that the primary centres are in the order of the given centrelist. Orbitals with primary centres which are not in centrelist come last.

2.)

Within each group of orbitals found for a given primary centre, those containing only one centre (lone pairs) are included first. The remaining ones are ordered so that the secondary atoms are in the order of centrelist. Orbitals with secondary centres which are not in centrelist come last.

3.)

If REVERT is given, the order in each localization group is reverted.

4.)

If GROUP is given, only the orbitals in the given group are reordered. igrp is 2 for closed shells and inactive orbitals, 1 for open-shells in single reference methods, and 3 for active orbitals in CASSCF calculations.

5.)

If THREIG is given, only orbitals with energies larger than the given value are reordered. eps must be negative. The remaining orbitals come last (first if REVERT is given).

Note that core orbitals are neither localized nor reordered.