When converting corn into ethanol, a lot of lignin and cellulosic material is left over. We could get energy out of the remains and turn them into other useful chemicals—if only we had controllable, efficient processes. To improve those processes, computational chemist Ariana Beste and experimental chemist A.C. Buchanan, both of Oak Ridge National Laboratory, explore thermochemical degradation of plant materials. They study how molecular structures influence networks of chemical reactions. The rate of a reaction depends on the height of energy barriers along paths between reactants and products and the fraction of molecules with enough energy to hurdle those barriers. One chemical reaction may lead to half a dozen products. Favoring a path that results in a specific product may necessitate understanding a hundred reaction paths. Petascale simulations on ORNL's Jaguar supercomputer can quickly calculate the proportion of molecules with the requisites for a specific reaction?a herculean statistical challenge. Calculating which bonds between atoms in a molecule have the lowest energies, for example, reveals the optimal shape for a molecule to assume. That knowledge can speed design of processes faster than do trial and error or expert insight.
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