Structural, elastic, electronic and optical investigations of fluoride-perovskite NaBeF3: first-principles calculations

The investigations of the pressure effects on structural, elastic, electronic and optical properties of fluoride-perovskite NaBeF3 are carried out for the first time using the full-potential linearised augmented plane wave plus local orbitals (FP-LAPW + lo) implemented in the Wien2K code. Local density approximation, generalised gradient approximation (GGA), EV-GGA and modified Becke-Johnson (mBJ) approaches are adopted to incorporate the exchange and correlation potential. The calculated structural properties are in good agreement with the previous results. The predicted indirect band gap (R-Gamma) is 11.87 eV for NaBeF3 indicating the insulating behaviour of the fluoride perovskite. The calculated formation and cohesion energies assert that this compound can be experimentally realised. The elastic properties indicate that NaBeF3 alloy is mechanically stable, ductile and anisotropic with a mixed bonding nature. The computed optical properties are in line with the Penn model and reveal its transparency for a large interval of energies. The investigation of the pressure effects on some physical properties of the studied alloy reveals that the compressibility module and the energy gaps increase with increasing pressure whereas the lattice constant decreases with increasing pressure. The investigated alloy can be used for high-frequency optical and optoelectronic devices.