The structural, electronic and magnetic properties of Ag4M and Ag4MCO (M = Sc-Zn) clusters

The structures, spectra and electronic and magnetic properties of Ag4M and Ag4MCO (M = Sc-Zn) clusters have been studied using density functional theory and CALYPSO structure searching method. Structural searches show that M atoms except Zn tend to occupy the highest coordination position in the ground state Ag4M and Ag4MCO clusters. Carbon monoxide is most easily adsorbed on Ag atom of Ag4Zn and M atom of other Ag4M. Infrared and Raman spectra, photoabsorption spectra and photoelectron spectra of Ag4M and Ag4MCO clusters are forecasted and can be used to identify these clusters from experiment. Analysis of electronic properties indicates that the adsorption of CO on Ag4M clusters changes the zero vibrational energy (ZPVE) and increases stability of the host clusters. Dopant atoms except for Zn improve the stability of silver cluster. The Ag4Ni cluster shows high chemical activity and maximum adsorption energy for carbon monoxide. Magnetism calculations reveal that the magnetic moment of Ag4M (M = Mn-Ni) cluster adsorbed by carbon monoxide is decreased by 2 mu(B). The change of magnetic moment makes it possible to be used as a nanomaterial for carbon monoxide detection. Simultaneously, it is found that the adsorption of CO on Ag4Cu cluster is a physical adsorption.