  Scrupulous theoretical study of 8Be nucleus states, both clustered and
non-clustered, is performed over a wide range of the excitation energies. The
quantities which characterize the degree of the alpha-clustering of these
states: spectroscopic factors, cluster form factors as well as the alpha-decay
widths are computed in the framework of an accurate ab initio approach
developed. Other basic properties of 8Be spectrum: the binding and excitation
energies, mean values of the isospin are calculated simultaneously. In the
majority of instances the results of the computations turn out to be in a good
agreement with the spectroscopic data. A number of predictions are made and
corresponding verification experiment is proposed. Prospects of the developed
approach for nuclear spectroscopy are demonstrated.
