Nucleation of a sodium droplet on C60

TL;DR

This study combines density functional calculations and empirical modeling to analyze how sodium atoms progressively coat a C60 molecule, revealing the formation of a sodium droplet at larger sizes and considering effects of ionization, thermalization, and electric fields.

Contribution

It introduces a combined computational approach to model sodium coating on C60, providing new insights into droplet formation and charge transfer effects.

Findings

Na_nC60 is homogeneously coated at small sizes

A sodium droplet forms for n>=8

External electric fields influence coating behavior

Abstract

We investigate theoretically the progressive coating of C60 by several sodium atoms. Density functional calculations using a nonlocal functional are performed for NaC60 and Na2C60 in various configurations. These data are used to construct an empirical atomistic model in order to treat larger sizes in a statistical and dynamical context. Fluctuating charges are incorporated to account for charge transfer between sodium and carbon atoms. By performing systematic global optimization in the size range 1<=n<=30, we find that Na_nC60 is homogeneously coated at small sizes, and that a growing droplet is formed above n=>8. The separate effects of single ionization and thermalization are also considered, as well as the changes due to a strong external electric field. The present results are discussed in the light of various experimental data.