Abstract
The stability of metallic thin ��lms is studied with free electron model, which is popularly known
as model of \particle in a box". A detailed theoretical framework is presented, along with discussion
on typical metals, such as Pb, Al, Ag, Na, and Be. This simple model is found to be able to describe
well the oscillation pattern of stability for continuous metallic ��lms. In particular, it yields even-odd
oscillations in the stability of Pb(111) ��lm, consistent with both experimental observation and ab
initio results. However, the free electron model is too crude to predict at what thickness the ��lm is
stable. The ��lm stability is further examined with a model of \particle in a corrugated box", where
a lattice potential is added along the vertical direction of the ��lm. The e��ect of lattice potential is
found not substantial.