Fig. S1. _Fig.S9

Fig. S1. Calculated direction-dependent (a) Young's modulus (b) electron and hole effective masses. (c) DP constant E1. Fig. S2. (a) Calculated real parts and (b) imaginary parts of the dielectric function for M-SbP3 along the polarization directions in the x and y axes. Fig. S3. Calculated the refractive index for M-SbP3 along the polarization directions in the x and y axes. Fig. S4. Calculated optical absorption of M-SbP3 along different polarization directions in the ultraviolet region. Fig. S5. Calculated optical absorption of M-SbP3 along different polarization directions in the visible region. Fig. S6. Calculated surface plot of valleys around valence band maximum and conduction band maximum for the M-SbP3. Fig. S7. Calculated stress-strain curves of M-SbP3 via uniaxial tensile strains along 30{degree sign}，110{degree sign} and 170{degree sign} direction. Fig. S8. Calculated stress-strain curves of M-SbP3 via uniaxial compressive strains along different direction in plane. Fig. S9. Calculated direction-dependent transverse piezoelectric coefficient of M-SbP3.