Lattice dynamical calculations have been performed for inverse spinel structure compounds MIn_{2}S_{4} (M = Mn and Co) using the proposed six parameter bond-bending force constant model. In this model, the short-range force constant is calculated by using the Taylor expansion of the potential energy in the harmonic approximation. This model is applied to study the zone-centre (Γ=0) phonon frequencies of inverse spinels MIn_{2}S_{4} (M = Mn and Co). The significant outcome of the present work is that the second neighbor interactions (octahedral bonding) are stronger than the first neighbor interactions (tetrahedral bonding). The zone-center phonon frequencies, calculated using these parameters, are found to be in very good agreement with the observed results.
Zone-centre Raman and infrared phonon frequencies for the spinel phases of oxides Li_{1+x}Ti_{2-x}O_4 (x=0.33) and Li_{1-y}Mg_{y}Ti_2O_4 (y=0.1, 0.3) of space group Fd3m have been calculated using a proposed short-range force constant model. In this model, the lattice potential energy is expanded using Taylor's expansion in the harmonic approximation. The calculated zone-centre phonon frequencies are in good agreement with the available experimental and previously calculated results.
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