Pyatnitskaya St. 48, 109017 Moscow, Russia
e-mail: dwiebe@inasan.rssi.ru
2Astrophysical Institute and University Observatory
Schillergäßchen 2-3, 07745 Jena, Germany
3Max Planck Institut für Astronomie
Königstuhl 17, D-69117 Heidelberg, Germany
Abstract:
In this paper we discuss possible ways to reduce the chemical reaction network
for the situations when the accurate abundances are only needed
for a limited number of species to compute, for example, such
dynamically important factors as the ionisation degree or
molecular cooling. We show that it is possible to reduce the number of
reactions and species so that the computational
time in some astrophysically interesting situations will be
reduced by orders of magnitude without appreciable loss of
accuracy. For example, to model magnetised dark clouds, self-consistently estimating
the ionisation degree with the UMIST 95 database,
one only needs to retain about 100 of 395 species with the
computational time cut by a factor of a hundred. In the case of
dynamical modelling with changing density, extinction, UV-intensity,
temperature etc., the reduced chemical network may help
to distinguish between feasible and non-feasible tasks.
