Structural, electronic and optical properties of novel carbonate fluorides ABCO3F (A=K, Rb, Cs; B=Ca, Sr)

•Effect of van der Waals interactions on structural properties.•Single-crystalline elastic constants and mechanical stability.•Electronic properties.•Linear optical properties.•Comparison of present computed compounds with other well known materials in non-linear optical materials.

In the present study, we performed first principles calculations on the electronic and optical properties of layered alkali–alkaline earth carbonate fluorides which attract attention in the domain of nonlinear optics. The calculated lattice parameters and volumes with and without inclusion of van der Waals (vdW) correction methods to standard density functional methods were compared with experiments. We observed that vdW interactions are predominant in RbCaCO3F and CsCaCO3F as compared with other computed compounds. The calculated bulk modulus from single crystal elastic constants reveals that these materials are all relatively harder than the KH2PO4 (KDP) crystal. We also found that these materials are wide band gap insulators as obtained from Tran–Blaha modified Becke–Johnson potential. The linear optical properties such as dielectric function, refractive indices, birefringence and absorption spectra are presented. Finally, the calculated birefringence values indicate that these crystals could be promising for producing phase matching in the deep ultra-violet region.

Graphical abstractThe co- and anti-parallel alignment of CO3 groups leads to larger and smaller SHG coefficients in (a) KCaCO3F, (b) KSrCO3F, (c) RbSrCO3F, (d) RbCaCO3F, and (e) CsCaCO3F.Figure optionsDownload full-size imageDownload as PowerPoint slide