Relativistic effects on geometry and electronic structure of small Pd-n species (n=1, 2, 4)

Relativistic effects on the properties of small neutral Pd-n species (n = 1 , 2, 4) and Pd-2(-) have been examined for the first time at the all-electr on level by performing scalar-relativistic and nonrelativistic density func tional calculations using a gradient-corrected density functional. Relativi stic effects are found to be important: They lead to a contraction of bond lengths, increase of vibrational frequencies, and a significant enhancement of binding energies. While relativistic effects are quite uniform for seve ral states of Pd-4, they vary for the states examined for Pd-2, leading to a change of ground state due to relativity. The calculated relativistic pro perties of Pd-2 and Pd-2(-) are in good agreement with available experiment al data from mass spectrometry and photoelectron spectroscopy. For Pd-4 thr ee-dimensional structures are found to be preferred to planar ones and many nearly isoenergetic isomers exist. (C) 1999 John Wiley & Sons, Inc.