In this work, all DFTB calculations were carried out using DFTB+, and we follow the training method described in the work of van den Bossche et al. to obtain two sets of DFTB parameters, named A and B, that differ from each other in the fitting of the band energy term. In group A, Li and Si band structures were fitted separately, while in group B the Li 7 Si 3 band structure was fitted. The choice of this structure for the adjustment of the band structure was based on the value of its formation energy, which is the lowest of the 5 main alloys (Li 15 Si 4 , Li 13 Si 4 , Li 12 Si 7 , Li 7 Si 3 and LiSi) as reported in The Materials Project, and reproduced in our calculations. The parameterization of the pseudoatomic orbitals and electronic density consists in optimizing the values of r 0 and s in equation 6 in order to fit the band structure to the reference DFT band structure. Table shows the obtained confinement parameters.