The reaction C₂H₂ + C₂H₂->C₄H₃ + H is of importance in the process of soot formation at high temperatures. The rate constant of this reaction was evalu­ated using the statistical theory of bi­molecular reactions via an intermediate complex. The parameters of the potential surface of the system were evaluated ab initio using the complete active space self-consistent field method and the sec­ond-order multi-reference Moeller-Plesset perturbation theory using the PC-GAMESS program package. The results of of rate constant calculations

k=2.5 ·10³ T^2.5exp(- 44400/RT)

are shown in the figure along with the experimental data. In the present case of strongly discordant experimental results, it can be supposed that theoretical results are more reliable.