The HF/6-31G(d)//HF/6-31G(d) theory level performs fairly well for generating optimized geometries and is relatively inexpensive with regards to computational cost. The use of this theory allows for a quick survey of the possible conformations that a given molecule might have. However, past experience has shown that it often over predicts the number of minima in comparison to an electron-correlated theory level using a larger basis set (e.g. B97-D3(BJ)/cc-pVTZ, MP2/cc-pVTZ). Due to the quick need of structural data, a majority of the initial calculations were done at HF/6-31G(d)//HF/6-31G(d) theory level.However, optimizations are continually being completed at more rigorous theory levels. Once completed and made available, these geometries should preferentially be considered.