Abstract: The equilibrium geometry and harmonic frequencies for the ground state of PD2 radical are calculated by using the coupled-cluster singles-doubles-approximate-triples CCSD(T) theory in combination with the aug-cc-pVTZ basis set. This approach yields the equilibrium bond length RPD of 0.142 36 nm,the bond angle ∠DPD of 91.806 9° and the dissociation energy De(DP-D) of 3.407 0 eV,respectively. The similarly obtained the harmonic frequencies ν1(a1) ,ν2(a1) and ν3(b2) are 1 709.376 0 cm-1,806.839 9 cm-1 and 1...