Ab initio description of clustering phenomena in spectra of light nuclei

An approach has been presented to take into account clustering properties of nuclei by the introduction of cluster components in the basis used in microscopic ab initio calculations and to calculate the cluster characteristics of nuclei by the projection of the $A$-nucleon wavefunction on wavefunctions of cluster channels. The binding energy, spectra, and cluster spectroscopic factors of the $\alpha+ t$ channel have been calculated for the ground and lower excited states of the $^7$Li nucleus. It has been shown that, except for a single state these states are strongly clustered, which is in qualitative agreement with spectroscopic data. It has also been found that the contribution of “noncluster” components to the binding energy is very large even in strongly clustered states.