The presented EHF and ECI methods were implemented in Python within a local development version of the SHARC package in a preliminary, semi-automatized fashion, where Gaussian 16 is called to conduct the site-state calculations for ECI and the ESP fits of the ground-state densities for EHF. The Merz-Singh-Kollman scheme was used to determine the spatial grid points for the ESP fitting. Auxiliary scripts were then implemented to parse the Gaussian output files (site energies, relevant density matrices and associated basis set information, relevant site dipole-moment matrix elements) and to construct the required site-state data that is not provided directly by Gaussian (see Appendix B for the details). The entire data set related to the site states is then passed to the EHF/ECI program which constructs the chosen ECI basis, performs truncation and spin adaptation, calculates the matrix H, diagonalizes H, and finally calculates the fullsystem dipole-moment matrix. Details about how the ECI formulas were practically evaluated are given in Appendix B.