Our species set, given in Table 2, contains 395 atomic and molecular
species involving the 12 elements H, He, C, N, O, Na, Mg, Si,P, S, Cl and
Fe. The species are ordered by number of atoms, with a sub-ordering given
by the number of H atoms, followed by the number of C atoms they contain.
For computational convenience,
some species are written in `shorthand', for example, 
represents methyl diacetylene, 
. We have included neutrals with
up to 12 atoms. In such cases, the proper chemical formula is contained
in parentheses after the `shorthand' in Table 3 which lists the permanent
electric dipole moments of the neutral species. Table 2 also lists the heats of
formation of the species contained
in the reaction set and can be used to check whether particular reactions are
exothermic or endothermic. These data, which were mostly provided by H-H Lee
(Ohio State University),
have been used to exclude a number of highly endothermic ion-neutral
reactions which were in the 1990 ratefile. Endothermic neutral-neutral
reactions are still contained in this release because such reactions
are important in shocked gas; ion-neutrals are relatively unimportant here,
although those which are important, for example the reactions of
(n = 0-2) with 
which initiate sulfur chemistry in shocked gas, are
included.
Table 2: Species and heats of formation in 
at 0 K
Table 2: continued
The permanent electric dipole moments for the 137 neutral molecules contained
in the species set are given, where available, in Table 3. The rate file
distinguishes between some isomers, such as HCN and HNC, as well as
and 
, and the dipole moments are listed for each
isomer. In those cases in which the ratefile does not distinguish isomers,
for example, the various forms of linear and cyclic 
, 
and
, the dipole moments for each form are given. The electric dipole
moments
are important for calculating reaction rate
coefficients appropriate for low temperatures (
). Various
formulae have been suggested, based on theoretical and experimental
approaches (Adams & Smith 1987; Troe 1987; Herbst & Leung 1986).
Table 3: Permanent electric dipole moments in Debye of the
neutral molecules
