  Wavefunctions of complex lanthanide atoms NdI, PmI and SmI, obtained via
multi-configuration Dirac-Fock method, are analyzed for density of states in
terms of partial densities, strength functions ($F_k(E)$), number of principal
components ($\xi_2(E)$) and occupancies ($\lan n_\alpha \ran^E$) of single
particle orbits using embedded Gaussian orthogonal ensemble of one plus
two-body random matrix ensembles [EGOE(1+2)]. It is seen that density of states
are in general multi-modal, $F_k(E)$'s exhibit variations as function of the
basis states energy and $\xi_2(E)$'s show structures arising from localized
states. The sources of these departures from EGOE(1+2) are investigated by
examining the partial densities, correlations between $F_k(E)$, $\xi_2(E)$ and
$\lan n_\alpha \ran^E$ and also by studying the structure of the Hamiltonian
matrices. These studies point out the operation of EGOE(1+2) but at the same
time suggest that weak admixing between well separated configurations should be
incorporated into EGOE(1+2) for more quantitative description of chaos and
localization in NdI, PmI and SmI.

Atomic Physics;General Physics