Molecular dynamics simulations of united atom nonentangled linear polyethylene models were utilized in order to systematically examine local orientational dynamics. In agreement with recent experiments and theoretical predictions, slow relaxation processes associated with motions of length scale of the order of chain dimensions are identified and analyzed with a method that allowed a model-free determination of their relative contribution to local orientational relaxation. Factors of intra- and intermolecular nature affecting their characteristics are discussed as well.