Experimentaly, the susceptibility is a linear function of the squared magnetization for BiMnO$_{3}$ [16]. In some papers [16, 20] this is rationalized on the basis of Landau-theory yet this it is not the case. In fact, in this phenomenological approach the inverse susceptibility is a linear function of the squared magnetization and it comes about from the renormalization of dielectric constant by the coupling. Explicitly this may be written [21] Δ F ≈ ( α$_{0}$ ( T − T$_{f}$ ) / 2 + γ/ 2 M $^{2}$) P $^{2}$+ ... = χ − 1 e P $^{2}$+ ... . In Fig. 5 we plot the predicted Landau theory value of Δ ϵ/ϵ (0) as a function of the squared magnetization. The dependence is none linear. In the inset of Fig. 5 we show the inverse dielectric susceptibility as a function of the squared magnetization to be linear within the framework of Landau theory. In case of χ$_{me}$ = 0 we calculate the inverse susceptibilities from the Landau functional as second derivative with respect to the order parameters, i.e. χ − 1 ϵ = ∂F 2 ∂P $_{2}$, χ − 1 m = ∂F 2 ∂M $_{2}$. Hence we obtain respectively: 11 ˜ χ − 1 m = T T$_{M}$ − 1 + ˜ M 2 + γ$_{m}$ T$_{f}$ T$_{M}$ ˜ P $^{2}$, (28) ˜ χ − 1 ϵ = l T$_{f}$ T$_{M}$ ( T T$_{M}$ − T$_{f}$ T$_{M}$$^{)}$ + γ$_{m}$ T$_{f}$ T$_{M}$ ˜ M 2 + 3 l$^{(}$ T$_{f}$ T$_{M}$$^{)}$$^{2}$ ˜ P $^{2}$, (27) FIG. 5: Field induced change in relative dielectric constant as a function of the square of the magnetization at 100 K. We assume that ( βa 2 $_{0}$T$_{M}$ ) / (4 πα$_{0}$bT$_{f}$ ) = 0 . 0008. Inset: Dependence of the inverse dielectric susceptibility vs. M $^{2}$. The data can be parametrized by the straight line: ˜ χ$_{e}$ (0) / ˜ χ$_{e}$ ( h ) = 1 , 233 + 1 , 071 M $^{2}$.