The Theoretical Calculation of Potential Energy Functions and Thermodynamic Functions for the Ground State of PuN

The potential energy function, force constant and spectroscopic data for the ground state X6Σ+ of PuN have been derived by the Gaussian 98 program with the B3LYP method, based on the approximation of relativistic effective core potential for Pu atom and all-electron 6-311G* basis set for N atom. The separated atomic group method is used to derive the possible electronic states for PuN. The ground states for Pu and N are4Su, respectively, which are the components of irreducible representation of the SU(n) group. PuN belongs to the C∞v group. The irreducible representations of the SU(n) group can be resolved into those of the C∞v group. That is, the possible electronic states of PuN are given. Pu(7Fg) and N(4Su) are resolved into the direct sum of C∞v. Their direct product and its reduction are the possible electronic states of PuN. Dissociation limit is derived by atomic and molecular reaction statics. The potential energy function of the ground state for PuN molecule is derived byab initiowith the B3LYP method, based on the approximation of relativistic effective core potential for Pu atom and all-electron 6-311G* basis set for N atom and fitting the Murrell-Sorbie (M-S ) function. In addition, the thermodynamic functionΔfH0、ΔS0andΔfG0of PuN(g) in the standard state are also calculated, which are -487.239 kJ/mol, 95.345 J/mol K and -515.6661 kJ/mol, respectively.