The electronic structure calculations are carried out by third-party computational chemistry programs interfaced with Newton-X. Newton-X CS uses Perl scripts to call such interfaces, execute the third-party programs, read their outputs, and use their results to propagate dynamics, compute nonadiabatic couplings, and simulate spectra. The numerical integration of the classical and quantum equations of motion, the surface hopping algorithm, and the Wigner sampling are executed by Fortran codes. The interfaces to third-party programs are defined in a shared Perl dictionary (hash), which controls default and execution parameters. The currently available interfaces are discussed in Section 5. The development of an interface to a new third-party program consists of defining its primary operation in the dictionary and preparing scripts to execute and read the outputs of that program.