Stiff rate equations:
H2 + Br2 Þ 2 HBr chain reaction
This mechanism search found its solution only with a special algorithm for 'stiff'
differential equations. The reason is the enormous ratio of the rate constants of the
elementary reactions involved (about 20 orders of magnitude!). One of them is the attack
of H2 by Br atoms, whose rate constant we have calculated by the LEPS method in
the previous example (see LEPS). The experimental results depicted
by crosses stem from the famous study of Bodenstein & Lind in 1906/07. For the
treatment of 'stiff' differential equations see e.g. J. Stoer & R. Bulirsch,
Numerical Analysis, Springer, New York, 1980, p. 462 ff.