Density functional theory molecular dynamics study of the Au_(25)(SR)~?_(18) cluster

摘要

The experimental structure of the Au25(SR)~?_(18) cluster has been previously accurately determined. However, it’s thermodynamical behaviour is not well studied. We performed molecular dynamics simulations of 10 ps duration on the model cluster Au25(SH)~?_(18) to gain information about the thermodynamical behaviour and stability of the cluster at temperatures between 300 K and 600 K. Our results suggest that the gold-sulfur bonds at the core-thiolate interface are the weakest ones in the system. However, the interface remains well defined during the simulations. The most significant structural changes take place in the gold core, where the ground state gold-gold bond length profile is completely changed by the thermal vibrations. The thermal movement does not affect the electronic structure notably. The HOMO and LUMO states broaden and the HOMO-LUMO gap narrows as a function of temperature, but the superatom electronic structure can be seen at all the temperatures clearly.