Thermodynamics of CO₂ adsorbed on palladium surface

The structures of PdCO2, PdCO, and PdH are optimized by the relativistic effective core potential (RECP) and the density functional theory B3P86 method. The results show that the stable geometry of Pd-CO2 molecule is plane structure. The ground state of PdCO2 is (X1A′) of Cs group. The structure parameters of RPdC, RCO, RC O′ and∠OCO′ are 0.203 0 nm, 0.118 3 nm, 0.121 0 nm and 154.215°,respectively. For PdCO molecule, the ground state is 1∑+, and the structure parameters of R(PdC), R(CO), and ∠PdCO are 0.183 4 nm, 0.114 0 nm, and 180°, respectively. The ground state of PdH is 2∑, and the bond length is 0.152 6 nm. Furthermore, the thermodynamic functions of PdCO2, PdCO, and PdH are also calculated according to electronic-vibration approximation. An