To optimize the supercell size selection, we compared the root-mean-square-error (RMSE) of IFC fitting and the computational costs (VASP runtime) for 9 cubic structures including body-centered cubic (Ba, Ca, Sr), zincblende (GaAs, GaP, BP) and rocksalt (NaCl, MgO, BaO) in 3 supercell sizes (Figure ) and averaged the results for each size (Figure ). For the consistency of the computational cost evaluation, we run all DFT calculations using 4 Cori-KNL nodes on NERSC (Intel Xeon Phi 7250 Processor: 68 cores@1.4GHz, 96GB DDR4, 16GB MCDRAM memory per node). The HiPhive step duration for different fitting methods (Figure ) was done on 1 NERSC Perlmutter CPU node (2x AMD EPYC 7713 Milan CPUs: 64 cores per CPU@2.0GHz, and 512GB DDR4 memory).