Size-dependent melting of nanocrystals: a self-consistent statistical approach

A self-consistent statistical method is used to describe size effects on melting of free nanocrystals. The melting transition is assumed to be directly related to evolution of high-temperature instability of the phonon subsystem of the crystal, caused by strong anharmonicity of atomic vibrations. We show that depression of the melting temperature of small free particles is mainly due to presence of surface atoms which are bound to smaller numbers of atoms than those of the interior. The melting temperatures of spherical nanocrystals of Ar and Au were calculated as functions of the inverse of their radii and compared with experimental and molecular dynamics data.