The value of Bulk modulus is not very large (15.3120 GPa), which is less than standard value of 40 GPa to specify any material a superhard [37]. While value of Young’s modulus (37.2189 GPa) specifies that LiBH₄ is a stiffer compound. If value of the Pugh’s criteria [36] \(\frac{B}{G}\) >1.75 the material is said to be ductile else brittle. In our case \(\frac{B}{G}\) is less than 1.75, thereby, declaring LiBH₄ a brittle material. Moreover, if \(\nu\) < 0.26 the material is deemed brittle else ductile [38], which is less than 0.26 for LiBH₄so it endorses its brittleness. If the value of an anisotropic factor (A) is equal to unity, the material is isotropic else anisotropic [39-40]. In our case, the value of anisotropic factor is less than unity for LiBH₄ which indicates its anisotropic behavior.

Dielectric function is deemed to be an important parameter, which is capable of illustrating the polarizability and energy loss function of any material. Particularly, its real part describes polarization of the materials, since dielectric function can be split into two parts; the real and imaginary parts which are drawn as a function of frequency and shown in figure 9. The complex dielectric function can be expressed through well-recognized Kramer-Kronig [32-41] relation as given below:

ℇ(ω) = ℇ₁(ω) + i ℇ₂(ω) (1)

Other than the dielectric function, we have also investigated frequency dependent energy loss function, refractive index, optical conductivity and reflectivity. Dielectric response of the material is mainly associated with the multiferroicity [42]. Penn^’s model can be expressed as [43]:

\(\varepsilon_{1}\left(0\right)=1+\left(\hslash\frac{\omega_{p}}{E_{g}}\right)^{2}\)(2)

In this relation \(E_{g}\) is energy gap and\(\ \omega_{p}\) is the plasma frequency.