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\section{Introduction}  Accurate benchmarks great help in developing more accurate semi-empirical methods. Especially true for intermolecular interactions. There are fewer benchmark sets for barrier heights. Unlike intermolecular interaction benchmarks tend to be less representative of biologically relevant reactions. Here we xx  Use of PM6, OMDx, and DFTB in QM/MM studies of barrier heights? Hediger's work.  Promise of semi-empirical in high throughput screening. Screening of barrier heights. SE reasonably accurate for intermolecular interactions and this has allowed Grimme ..