All-electron scalar relativistic calculation on the interaction between nitric monoxide and small gold cluster

An all-electron scalar relativistic calculation on AunNO (n = 1–10) clusters has been performed by using density functional theory with the generalized gradient approximation at the PW91 level. The small gold cluster would like to bond with nitric and the nitric monoxide molecule prefers to occupy the on-top and single fold coordination site. The Aun structures in all AunNO clusters are only distorted slightly and still keep the planar structures. With the bend of Au-N-O bond, the structures of AunNO clusters evolve from the 2D structure to 3D structure. The most favorable adsorption between small gold cluster and nitric monoxide molecule takes place in the case that nitric monoxide molecule is adsorbed onto an odd-numbered pure Aun cluster and becomes odd-numbered AunNO cluster with even number of valence electrons. The scalar relativistic effect strengthens the Au–Au, Au–N interaction and weakens the N–O interaction, appearing as the shorter Au–Au, Au–N bond-length and the longer N–O bond-length. The differences between our work and previous work are believed to be the reflection of the scalar relativistic effect.