Efficient first-principles evaluation of thermodynamic stability, physical properties and photocatalytic performance of alkali-metal tantalates

We report the structure, stability, electronic, optical, and photocatalytic properties of sodium and potassium tantalates (NaTaO₃ and KTaO₃) by employing meta-GGA level DFT calculations. Our results show that the structural, mechanical, vibrational, and energetic properties computed using SCAN meta-GGA are in excellent agreement with experimental data compared to earlier calculations performed using semi-local and hybrid-DFT calculations. Moreover, we also show that the employment of TB09 meta-GGA with spin-orbit coupling facilitates reliable description of the electronic properties of NaTaO₃ and KTaO₃. The optical absorption coefficients of orthorhombic NaTaO₃ and cubic KTaO₃ are also reported and their potential for photocatalytic hydrogen production from overall water molecule splitting has been examined. Our results clearly show that accurate determination of physical properties of NaTaO₃ and KTaO₃ can be achieved by combining SCAN and TB09 meta-GGAs at a significantly lower computational cost compared to computationally demanding hybrid-DFT and GW calculations.