Local magnetic moments; Magnetic order; Optimized structures; PFT calculations A-density; Average binding energy; B3LYP/LanL2DZ; Cluster sizes; Coordination number; Geometrical structure; Ground-state structures; Higher-dimensional; HOMO-LUMO gaps; Local magnetic moments; Magnetic orders; Niobium cluster; Optimized structures; Atoms; Bond length; Magnetic materials; Magnetic moments; Niobium; Nuclear energy; Potential energy; Binding energy