We have developed a new DFTB parameterization scheme aiming to optimize other observables beyond absolute energies. We used this scheme to construct a DFTB model with an optimal prediction of formation energies for several crystallines and amorphous structures in a wide range of compositions. In the case of pure amorphous silicon, which exhibits the largest associated error in the prediction of formation energies, the experimental radial distribution function was perfectly reproduced by the model. The excellent performance shown by this model in comparison with DFT, in addition to being more than 1000 The vertical dashed black lines show where the peaks of crystalline silicon would be at 0 K. An excellent agreement is found with parameterization B. times faster, allows us to consider it as the potential of choice for future simulations of Li x Si alloys.