We are seeking to combine the reliability of the structures and energies obtained from quantum mechanical methods with the insights given by larger scale simulations, which are better able to search configurational space. We will discuss our recent work using quantum mechanical methods, based on DFT, which have been applied to the study of a number of solids. Al2O3, CeO2, MnO2 and CaCO3, and compare these with results using atomistic simulation where the forces between atoms are modelled using interatomic potentials. The results show that such quantum methods can be used successfully to screen the different potential models and where necessary, provide sufficient data to allow us to re-consider the potential models. In addition, we show examples where the quantum based methods can give further insights into the reactivity, particularly of surfaces. However, it still remains computationally expensive to search all possible configurations and by using the atomistic simulations to search through different configurations we can identify new structures which can be verified with the quantum based simulations.