Abstracts Book - IMRC 2018

• SA2-O005
STABILITY AND CHARGE DISTRIBUTION IN SILVER, GOLD AND
BIMETALLIC CLUSTERS: THE Ag44-xAux(SR)30 4- AND Ag25-xAux(SR)18 1-
CASES
Cercis Morera Boado 1 , Francisco Hidalgo 2 , Cecilia Noguez 1
1 Instituto de Física - Universidad Nacional Autónoma de México, Física Química, Mexico.
2
Universidad Autónoma Metropolitana, Ciencias Básicas, Mexico.
Metal nanoparticles have shown a substantial impact across a wide range of
fields such as catalysis, optoelectronics, sensing, photochemistry, energy
conversion and medicine. Among them, ligand protected Au-nanoparticles have
been more studied due to its stability and high affinity to the thiol group, which
is present in many different organic molecules. On the other hand, silver
nanoparticles are known to be less noble than their gold analogues. Clusters
with different number of Au atoms capped with the same ligand have been
found, whereas silver clusters have a much more constrained relationship
between size and ligand. One of the main characteristics of these ligand
protected metal nanoparticles is their ultrastability, recently observed in silverprotected
clusters. Although the outstanding stability of these nanoparticles is
attributed to the fulfillment of a closed-shell electron configuration rule with
large HOMO-LUMO gaps, the key factors causing its ultrastability are still
unclear. Therefore, to gain some insights on the ultrastability in these metallic
clusters, in this work the atomic configurations and charge distributions of Ag44-
xAuxSR30 4- and Ag25-xAuxSR18 1- with R= -H, -CH3, –C6H5, –C6H5NO2, –C6H5NH2, –
pMBA, –C6H13 have been analyzed by means of DFT. The analysis of charge
distributions of silver, gold and different bimetallic clusters help us to
understand where the negative charge is located and how this distribution
affects their relative stabilities. A different charge distribution is presented for
experimentally existent clusters. Thus, the origin of the ultrastabilities of these
clusters, the possibility of the existence of different ligand configurations, the
charge distribution and the role of the –SR ligands in their stabilities are
discussed.
Acknowledgment: AFORS
Keywords: Metal Nanoparticles, Charge Distribution, Density Functional Theory
Presenting authors email: cmorera@fisica.unam.mx