Determination of the rate constant for sulfur recombination by quasiclassical trajectory calculations

The sulfur recombination reaction has been thought of as one of the most important chemical reactions in the volcanic activities of the planet. It is also important in determining the propagation of elemental sulfur in the atmosphere. There have been two experimental attempts to determine the reaction rate of the S+S-->S(2) recombination, however their results differ by four orders of magnitude. In this work, we determine the rate constant of S+S-->S(2) from quasiclassical trajectory calculations. The third order rate constant at 298.15 K predicted by the present calculations is 4.19 x 10(-33) cm(6) molecules(-2) s(-1), which is in excellent agreement with the determination of Fair and Thrush [Trans. Faraday Soc. 65, 1208 (1969)]. The temperature dependent rate constant is determined to be 3.94 x 10(-33) exp[205.56(1T-1298.15)], which was determined from the temperature range of 100-500 K.