Computer-aided methods for simulating confined nanodevices are disclosed. In example implementations, atomic-scale model of the nanodevices are generated so that dimensions and materials are specified. Then, band structures which comprise wave functions and Eigen energies are calculated using First Principles Methods (FPM). Effective mass modeled which comprise wave functions and Eigen energies are generated. After that, spatial wave functions of the calculated FPM band structures are mapped to the generated effective mass band structures wave functions by considering global behavior. In response to the mapping, generated effective mass models are fitted to calculated FPM energies so that approximate electronic band structures of the confined nanodevices are modeled. Computer programs for carrying out the methods, data media and computer systems are also disclosed.