PM3 semiempirical electronic structure calculation of capped and uncapped CdS nanoparticles

In this paper, CdS nanoparticles of various sizes are theoretically studied . We have used the PM3 semiempirical Hamiltonian of Stewart to compute thei r ground state electronic structures on the assumed zincblende like geometr ies, optimized with the SYBYL molecular mechanics force field. Suitable cap ping agents induce surface modification of these nanoparticles. In order to reduce the computational cost, the experimental capping agents (2-ethyl-he xanoate ions) are modeled by formiate ions. We compare the stability of the naked and capped nanoparticles in the gas phase with the solvated species in the dimethylsulfoxide solvent. The evolution of the HOMO-LUMO gaps has b een determined for these CdS particles, both naked and capped. (C) 1999 Act a Metallurgica Inc.