This paper presents first principles quantum-chemical calculations of vibrational spectra of SrMoO4 clusters and clusters of Sr0.4Bi0.4MoO4, a cation-deficient scheelite-like phase. The calculation results are compared to experimental Raman spectroscopy data. The effects of bismuth incorporation and structural disorder in the clusters show up as additional scissoring vibrations of oxygens. © 2023, Pleiades Publishing, Ltd.