The James Webb Space Telescope (JWST) has opened new frontiers in observing the interstellar medium, with the nitrile (4.4 um) stretching band serving as a primary diagnostic tool for nitrogen-bearing polycyclic aromatic hydrocarbons (cyano-PAHs). While several recent studies have addressed the anharmonic spectra of specific cyano-PAH species, a comprehensive, systematic template library that spans a broad range of molecular conditions remains missing. To accurately interpret high-resolution astronomical observations, it is imperative to move beyond fragmented data and establish a rigorous, large-scale spectral database. This project proposes a systematic computational investigation to generate high-accuracy anharmonic infrared spectra for a diverse library of cyano-PAHs. By leveraging the complementary capabilities of Gaussian, CP2K, and ORCA, we will perform comprehensive quantum chemical calculations across a wide parameter space. Our methodology employs Density Functional Theory (DFT) for structural optimization and Second-Order Vibrational Perturbation Theory (VPT2) to rigorously capture anharmonic effects, Fermi resonances, and combination bands essential for matching the sub-peak structures in high-resolution spectra.The research framework is designed to explore the spectral dependence on three critical physical factors: Charge States: Modeling both neutral and ionic (cationic/anionic) species to reflect the ionization environments of star-forming regions. Isomeric Substitution: Investigating the "1-position enhancement" and other site-specific effects by covering a wide range of nitrogen-substitution positions on various aromatic cores. Molecular Size Scaling: Scaling calculations from small aromatics to large PAHs to derive robust trends in nitrile intensity as a function of the number of carbon atoms (N_C). This systematic database will provide the first unified template set suitable for direct comparison with JWST/NIRSpec and MIRI observational data. By establishing high-precision spectral profiles for various charge states and isomeric distributions, our work will significantly reduce systematic uncertainties in nitrogen abundance derivations. The resulting data will serve as an essential foundation for modeling the chemical evolution of nitrogen-heterocycles in the diffuse interstellar medium and protoplanetary disks, providing a robust quantitative link between quantum chemical predictions and infrared astronomical observations.