Theoretical study of potential energy surfaces for interactions of Pd2 with CO

Potential energy surfaces for the low-lying electronic states of the Pd2CO complex are studied using the second order perturbation theory of Mo/ller and Plesset (MP2) and the complete active space multiconfiguration self-consistent-field method (CASSCF) followed by large scale multireference singles+doubles configuration interaction (MRSDCI) computations that included up to 3.95 million configuration spin functions (CSFs). The bridged structure was found to be more stable by 1.3–1.5 eV compared with the linear structure depending on the level of theory. The calculated MP2 vibrational frequencies for Pd2CO are compared with the experimentally determined values for different chemisorptive sites. The properties of Pd2CO are compared with the corresponding properties of Pt2CO.