The feasibility of spin-forbidden cooling of the InH molecule is investigated based on ab initio quantum chemistry calculations.The potential energy curves for the X1Σ+0,a3Π0-,a3Π0+,a3H1,a3Π2,A1Π1,13Σ+0-,and 13Σ+1 states of InH are obtained based on multi-reference configuration interaction plus the Davidson corrections method.The calculated spectroscopic constants are in good agreement with the available experimental data.In addition,the influences of the active space and spin-orbit coupling effects on the potential energy curves and spectroscopic constants are also studied.For Re of a3Π0-,a3Π0+,a3Π1,and a3H2 states,the error from large active space is small.The potential energy curve of the A1Π1 state is not smooth for small active space.The spin-orbit coupling effects have great influences on the potential well depth and equilibrium intuclear distance of the A1Π state.The Franck-Condon factors and radiative lifetimes are obtained on the basis of the transition dipole moments of the a3Π0+ → X1Σ+0+,a3Π1 → X1Σ+0+,and A1ΠΠ1 → X1Σ+0+ transitions.Our calculation indicates that the a3Π1 (v’=0) → X1Σ+0+ (v =0) transition provides a highly diagonally distributed FranckCondon factor and a short radiative lifetime for the a3Π1 state,which can ensure rapid and efficient laser cooling of InH.The proposed laser drives a3Π1 → X1Σ0++ transitions by using three wavelengths.