Stress Formulation in the All-Electron Full-Potential Linearized Augmented Plane Wave Method

Formulation for calculating stress tensors based on the all-electron full-potential linearized augmented plane wave method with the basis functions proposed by Solar and Williams is presented. Validity of the formulation is tested by comparing the pressure obtained as the trace of stress tensor with that estimated from total energies on Si, Al, C, Fe, Cu, W, GaAs, L1(2) Cu3Au, and cubic BaTiO3. Results show that pressure is estimated within the accuracy of less than 0.05 GPa for Al and Si and about 0.1 GPa for the others. Calculations of the shear elastic constant C-44 for Mo, W, and Cu show that the shear components of the stress tensor are also precisely computed with the present formulation.