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

• SCAN and TB09 meta-GGAs employed for accurately evaluation of alkali-metal tantalates • Thermodynamic stability of orthorhombic NaTaO 3 and cubic KTO 3 are confirmed in agreement with experiments • Elastic constants, phonon frequencies, band gaps, band edge potentials and optical abortion are reported • Photocatalytic potential of pristine NaTaO 3 and KTaO 3 are confirmed in the UV region We report the structure , stability, electronic, optical, and photocatalytic properties of sodium and potassium tantalates (NaTaO 3 and KTaO 3 ) 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 NaTaO 3 and KTaO 3 . The optical absorption coefficients of orthorhombic NaTaO 3 and cubic KTaO 3 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 NaTaO 3 and KTaO 3 can be achieved by combining SCAN andTB09 meta-GGAs at a significantly lower computational cost compared to computationally demanding hybrid-DFT and GW calculations.