The ARCHIVE file contains a data-set suitable for submission to
MOPAC. If, in addition to this data-set, the Z-matrix for Gaussian input
is wanted, then AIGOUT (ab initio geometry output), should be used.

The Z-matrix is in full Gaussian form. Symmetry, where present, will be
correctly defined. Names of symbolics will be those used if the original
geometry was in Gaussian format, otherwise 'logical' names will be used.
Logical names are of form
<t><a><b>[<c>][<d>] where <t> is
'r' for bond length, 'a' for angle, or 'd' for dihedral, <a> is the
atom number, <b> is the atom with which <a> is related,
<c>, if present, is the atom number to which <a> makes an
angle, and <d>, if present, is the atom number to which <a>
makes a dihedral.