The damping coefficient is the largest for HEA for any of the metals, making the material less prone to a high quality factor Q resonance as compared with a single metal. The damping constant is also closely related to the absorption loss and is strongly affected by the crystalline state of the material, e.g. strucutal defects such as grain boundaries, dislocations, stacking faults. The very sharp peaks obtained by X-ray crystal structure analysis indicate that the variation in the size of the grain boundaries is very well suppressed. Hence, a highly homogeneous structure is formed. However, considering the lattice constant of the crystals, it is difficult to conclude that a single phase is included in the HEA. Considering the lattice constants of the crystals, the atomic radius of a single atom of 140 pm, which is assumed from the lattice constant of the HEA, a formation of a single phase HEA is considered. HEA has a larger lattice constant as compared with Cu, Pt, and Pd. It is assumed that the repulsion between nuclei and elongation of bonds due to the decrease in the inter-atomic distance causes a distorted geometry. This distortion between the crystal lattice and atomic radii is thought to be responsible for the increased damping of the optical response of the electron. At the plasmon resonance, the balance between the oscillation of free electrons and the loss and damping caused by various factors are at the interplay. In the present system, we could improve absorption over a wide range of wavelengths by coincidence. It is important to continue to analyze the permittivity of different HEA systems, find a methodology to precisely control these Drude and Lorenz parameters, and to establish a unified method for material search to find a material with a resonance line width comparable to that of Au Ag Cu, but with enhanced absorption. Having obtained the complex permittivity of the newly engineered metallic material, the resonance properties were calculated using FDTD simulations. Simultaneously, the scattering cross-sections (σ sca )and absorption cross-sections (σ abs ) can also be quantitatively bluedetermined using the proposed method.