The resulting geometries and energies are checked after each fitness evaluation to ensure that the local optimization was successful, as it may happen that the initial structures R generated by the GA operators have clashes or are so deformed that it becomes difficult for the local optimizer to converge to a stable (local) minimum, especially within the first few generations. In this uncommon case, individuals from non-converged optimizations are simply ignored and replaced in the next generation by assigning them a very high (unfavorable) fitness value.