Electronic structures, stabilities and spectroscopic properties of Pb_mSi_n (m + n ≤ 6) clusters

Abstract

Electronic structures of neutral lead–silicon clusters of up to six atoms are determined by global optimization of the potential energy hyper surface using Metropolis Monte Carlo and genetic algorithm (GA) methods followed by a bond strength propensity model, and by local optimization using density functional theory at the B3LYP/aug-cc-pVTZ-pp level. For each cluster, geometries of those stable isomers whose relative energies are within 1.0 eV are reported. Average binding energy per atom, band gap, ionization potential (IP), electron affinity (EA), and vertical detachment energy of the most stable isomer of each type of cluster are computed to study their dependences on the size of the cluster. Polarizability, chemical potential, hardness and electrophilicity index of the most stable isomers are estimated to study their relative stabilities and chemical reactivities. Relative strengths of metal–metal interactions are determined from a study of all one-step fragmentation processes. IR intensities and Raman activities for all the vibrational modes of the most stable isomers are calculated.

Keywords:

• lead–silicon clusters
• binding energy
• reactivity descriptor
• fragmentation energy
• IR and Raman-active modes

Acknowledgments

The financial assistance provided by the CSIR, Government of India through the scheme 01(2381)/10/EMR-II is gratefully acknowledged.