<p>Inorganic molecular cluster (IMC) is a unique class of materials which have potential to exhibit periodicity like those of traditional clusters but composed of isolated molecular units. This work reports features of the IMCs investigated using first-principles calculations of vibrational and optical properties of antimony oxides (Sb₄O₆), phosphorous oxides (P₄O₆) and phosphorous selenide (P₄Se₃) at zero dimensions. The work is performed via Density Functional Theory (DFT) to calculate Frank Condon spectroscopy (FCS), modes of vibrations, vibrational circular dichroism (VCD) spectra, circular dichroism (CD) spectra, UV-vis spectroscopy and excitation spectra of the materials. The modes of vibrations and active modes of the excitations for electrically resolved vibrational spectra of the structures are also calculated. The stability of the clusters was investigated through the AIMD simulation at 300&#xa0;K temperature. The molecular units of the materials comprising of dimer exhibited vibrational modes represented by several displacement vectors emerging from various atoms converge at a point analogous to a focal point. The molecular clusters Sb₄O₆, P₄Se₃ and P₄O₆ are found optically active at 4.9, 2.20 and 4.30&#xa0;eV respectively.</p>