molecular states in a microscopic four α model.

Abstract: The 16O nucleus is investigated within a four α multicluster model. The generator coordinate method combined with the microscopic R-matrix method is used to determine bound and resonant states. The 12C nucleus is described by 3 α clusters located at the apexes of isosceles triangles. We optimize the generator coordinates to get a reasonable description of the – energy gap, where the is the so-called Hoyle state, considered as a 3 α state. Our calculations mainly focus on resonances located near the threshold. We emphasize the difficulty to interpret broad resonant states and we show that bound state approximation methods are not well adapted in the context of our study. An R-matrix analysis suggests the existence of , and molecular states which present a significant structure, and which may form a rotational band. [Copyright &y& Elsevier]