A new capability of our well-known NEMO 3-D simulator (Ref. Klimeck et al., 2007 ) is introduced by carefully investigating the utility of semiconductor quantum dots as infrared photodetectors at a wavelength of 1.2.5 . We not only present a detailed description of the simulation methodology coupled to the atomistic sp3d5s∗ tight-binding band model, but also validate the suggested methodology with a focus on a proof of principle on small GaAs quantum dots (QDs). Then, we move the simulation scope to optical properties of realistically sized dome-shaped InAs/GaAs QDs that are grown by self- assembly and typically contain a few million atoms. Performing numerical experiments with a variation in QD size, we not only show that the strength of ground state inter- band light transitions can be optimized via QD size-engineering, but also find that the hole ground state wavefunction serves as a control factor of transition strengths. Finally, we briefly introduce the web-based cyber infrastructure that is developed as a government- funded project to support online education and research via TCAD simulations. This work not only serves as a useful guideline to experimentalists for potential device designs and other modelers for the self-development of optical TCAD, but also provides a good chance to learn about the science gateway project ongoing in the Republic of Korea.