Getting input data for the calculations

Input data are needed to calculate k E) values, density of states functions, collision frequencies, and so on. The specihc type of required parameters depends on the selected method. If the goal is to do a back 

A general strategy to obtain the required input parameters could involve the following sequence  

Maybe the best resource for input parameters are original publications, because these provide not just the data per se but also the context in which they were obtained and often an estimate of their uncertainties. Obvious sources for input data are, for example, kinetic studies (high-pressure rate expressions) and spectroscopic measurements (molecular properties) 

After all literature sources for input data are exhausted, consider estimating the missing parameters. This can be done intuitively by relating the unknown parameters to related data, or one can use 

Finally, use theoretical methods to calculate missing parameters. The most powerful tool in this regard are ab initio calculations, which provide all basic molecular parameters needed to calculate thermodynamic properties (via statistical mechanics methods) and kinetic data (via transition state theory). Some aspects of this approach will be outlined further below. 

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