Time-dependent master equation simulation of complex elementary reactions in combustion: Application to the reaction of (CH2)-C-1 with C2H2 from 300-2000 K

Computational simulations of the title reaction are presented, covering a t emperature range from 300 to 2000 K. At lower temperatures we find that ini tial formation of the cyclopropene complex by addition of methylene to acet ylene is irreversible, as is the stabilisation process via collisional ener gy transfer. Product branching between propargyl and the stable isomers is predicted at 300 K as a function of pressure for the first time. At interme diate temperatures (1200 K), complex temporal evolution involving multiple steady states begins to emerge. At high temperatures (2000 K) the timescale for subsequent unimolecular decay of thermalized intermediates begins to i mpinge on the timescale for reaction of methylene, such that the rate of fo rmation of propargyl product does not admit a simple analysis in terms of a single time-independent rate constant until the methylene supply becomes d epleted. Likewise, at the elevated temperatures the thermalized intermediat es cannot be regarded as irreversible product channels. Our solution algori thm involves spectral propagation of a symmetrised version of the discretiz ed master equation matrix, and is implemented in a high precision environme nt which makes hitherto unachievable low-temperature modelling a reality.