The mixing between near-spherical and well-deformed shapes in nuclei is investigated by a phenomenological Bohr Hamiltonian employing a double-minimum collective potential. For this purpose, the Hamiltonian is diagonalized in a Bessel-Fourier expanded basis [1]. The evolution of spectral and dynamical features of the model is studied between different shapes of the potential amended with the centrifugal contribution from the kinetic energy and subjected to the condition of degenerate minima [2]. The amount of quantum tunneling between the two deformation wells is found to dictate whether the system exhibits shape coexistence with various degrees of mixing or simple shape fluctuation phenomena. The effect of deformation configuration mixing is exemplified on few nuclei known for shape coexistence.

[1] R. Budaca, P. Buganu, and A. I. Budaca, Bohr model description of the critical point for the first order shape phase transition, Physics Letters B 776, 26 (2018).
[2] R. Budaca and A. I. Budaca Coexistence, mixing and fluctuation of nuclear shapes, EPL 123, 42001 (2018).