Construction of amorphous structures
Abstract
Conditions for modeling amorphous structures from first principles are minimization of the free energy and a certain degree of continuity with the liquid state. We achieve the minimization of the total energy due to pair potentials or pseudopotentials by a variational method and the use of a seed structure as boundary condition. The seed structure, which has to be selected from several possible structures according to the shape of the pseudopotential is more or less propagated by these so-constructed structures. A rather flat pseudo-potential is required for a bcc solution, while a sharper one results in an amorphous structure which extends the icosahedron structure. Planar cuts, the pair-distribution function, packing efficiency, energy, and coordination number are derived for this fairly stable complex structure. Numerous excited states of low energy are shown to occur because of inhomogeneities and defects such as vacancies.