The main impediment to practical application is the toxicity of lead ions in halide perovskite absorbing materials. Computing tools based on density functional theory (DFT) were used to predict the intrinsic properties of potential for double perovskites to be effective and suitable for optoelectronic applications, replacing the conventional lead halide perovskites with environmentally friendly elements. The Generalized Gradient Approximation (GGA) with Perdew-Burke-Ernzerhof (PBE) functional was used to screen homovalent alternatives for B and X-site ions in vacancy-ordered double perovskite Cs₂BX₆ (B=Pt, Ni, X= Cl, Br) for solar cell applications. Using the GGA with PBE functional, the band gap was calculated to be 1.411 eV, 0.482 eV, and 0.378 eV for the Cs₂PtBr₆, Cs₂NiCl₆, and Cs₂NiBr₆, respectively. The experimental band gap value of mother crystal's (Cs₂PtBr₆) was at 1.42 eV. Next, the DOS, PDOS and optical properties were computed using GGA with PBE functional. Then, the local density approximation (LDA) with Ceperley and Alder with Perdew and Zunger (CA-PZ) was executed to compare the GGA with PBE for electronic band structure. In addition, the OTFG ultra soft, OTFG norm conserving, ultra soft and norm conserving methods of pseudopotential were used for both GGA with PBE and LDA with CA-PZ to make and ensure the right or accurate DFT functional for those crystals. At last, the optical properties and their toxicity have been evaluated for their rational design of potential double perovskite materials with improved optoelectronic properties.

Natural organic pigments such as carotenoids, betalains, anthocyanins, and carminic acid are notably found as safer food preservatives compared to other harmful synthetic chemicals. Due to glycosylation and acylation, betalains exhibit a broad-spectrum antimicrobial functionality with protection against degenerative diseases. Thus, betalains have been investigated as a potential bacterial inhibitor for food preservative applications. Initially, 36 betalain derivatives have been taken for primary screening using molecular docking. Afterward, the top ten ligands are taken for further study and analysis. The results of Prediction of Activity Spectrum of Substances (PASS) assured the antibacterial capabilities of betalains, and Lipinski's rule-of-five ensures the acceptability of the selected ligands as antibacterial inhibitors. The bacterial pathogens, such as C. botulinum (3FIE), E. coli (2ZWK), and S. typhi (3UU2) are selected for molecular docking by these betalain pigments. Furthermore, ADMET investigations and QSAR studies are performed to check insights into the bacterial inhibition process. Most active and common binding sides were observed at GLY159, ASN165, and SER166 for C. botulinum, at ASP8, LYS40, and TRP50 for E. coli; and at ARG37, GLN5, and ARG74 for S. typhi. The present study clearly shows an excellent insight towards the invention of plant-based new organic inhibitors to face the challenges of bacterial-resistant common food preservatives.