This research isolates, characterizes, and studies the computational and frequency calculations of emodin, extracted from the leaf extract of Pteridium acquilinum leaves using methanol. Vacuum liquid and tin layer Chromatography was used for the purification of the molecule. The (VLC purified), fraction was analyzed by Nuclear magnetic resonance (NMR) and the chemical structure of the compound isolated (anthraquinone), was confirmed by 1H & 13C-NMR analyses  as emodin (C15H10O5). Computational and frequency studies have been done on the isolated molecule. Optimized geometry, IR frequencies, Bond distances (R) and angles (A), Dipole moments and other parameters have been computationally determined for the isolated molecule from quantum chemical calculations using the GAUSSIAN 09 retinue programs. Experimentally determined and computationally measured IR frequencies agree perfectly with each other. Computational studies can be used to predict unobserved chemical phenomena like design of new drugs and materials such as the positions of constituent atoms in relationship to their relative and absolute energies, electronic charge densities, dipoles, higher multiple moments, vibrational frequencies, relativity or other spectroscopic quantities and cross sections for collision with other molecules. This is the first time this anthraquinone, [emodin], with most of the parameters examined is reported from P. aquilinum.