41 citations · 137 across the 35 of their papers we have counts for
5 papers · 1 filter
Aperiodic packings of clusters obtained by projection
Nicolae Cotfas
Atomic-resolution electron microscope images show that a quasicrystal is a quasiperiodic packing of clusters. The outer atomic shells of multi-shell clusters occuring in quasicryst…
Modified strip projection method
Nicolae Cotfas
The diffraction image of a quasicrystal admits a finite group G as a symmetry group, and the quasicrystal can be regarded as a quasiperiodic packing of copies of a G-cluster C, joi…
Shape invariant hypergeometric type operators with application to quantum mechanics
Nicolae Cotfas
A hypergeometric type equation satisfying certain conditions defines either a finite or an infinite system of orthogonal polynomials. The associated special functions are eigenfunc…
Systems of orthogonal polynomials defined by hypergeometric type equations with application to quantum mechanics
Nicolae Cotfas
A hypergeometric type equation satisfying certain conditions defines either a finite or an infinite system of orthogonal polynomials. We present in a unified and explicit way all t…
On the linear representations of the symmetry groups of single-wall carbon nanotubes
Nicolae Cotfas
The positions of atoms forming a carbon nanotube are usually described by using a system of generators of the symmetry group. Each atomic position corresponds to an element of the…