We have proposed a possible crystal structure for the cluster-assemble
d solid Al12C(Si), and its electronic structures and stability have be
en studied in the framework of density functional theory and ab initio
molecular dynamics. We find that Al12C(Si) clusters are condensed by
van der Waals force, with a very small cohesive energy of similar to 1
.1 eV. The combined steepest descent on ions shows that upon the forma
tion of solid the relaxation of atomic distances in the Al12C(Si) clus
ter is very small. The stability of the Al12C solid is also confirmed
by a dynamical simulation at low temperature.