Abstract: Based on the relativistic effective core potential (RECP/SDD) for Pd atom and AUG-cc-pVTZ basis function for N atom, the structure of PdN and PdN2 have been optimized using B3LYP method, and the thermodynamic functions for PdN and PdN2 have been calculated. The vibrational energy, electronic and vibrational entropy of the molecules in their solid states are assumed, ΔHӨ, ΔSӨ and ΔGӨ and nitrogen equilibrium pressures of the nitrogenating reaction have been calculated based on this approximation. It is deduced that at 1.01325×105 Pa and 298.15～998.15 K, adsorption of N2 on Pd surface proceeds as Pd(s) + N2 = PdN2(s). The formation enthalpy for PdN(s) at 298.15 K is 254.37 kJ·mol-1, and the formation enthalpy for PdN2(s) at 298.15 K is －80.59 kJ·mol-1. The nitrogen equilibrium pressure is about 100 times of the hydrogen equilibrium pressure, so it is difficult for Pd to adsorb N2.

Key words: PdN, PdN2, Density functional theory, Thermodynamic function, Equilibrium pressure, Adsorption behavior