Benchmark calculations of thermal reaction rates. II. Direct calculation of the flux autocorrelation function for a canonical ensemble

The thermal rate coefficient for the benchmark reaction H+H2→H2+H with zero total angular momentum is calculated by an ℒ2 basis-set evaluation of the flux autocorrelation function. This involves the direct evaluation of the thermally averaged flux operator without calculating any state-to-state reaction probabilities. The results are internally converged to 0.1% and agree with the totally independent results of the previous paper to within 0.03%. This confirms that the correlation-function approach is stable enough to converge practical calculations to three or more significant figures, which is adequate for all purposes, and that the calculations of this and the previous paper may be used to test the convergence and accuracy of other methods for calculating canonical-ensemble reaction rates.