The dynamic mechanism of the Thomas-Ehrman shift is studied in three-cluster
systems by example of 16Ne and 16C isobaric mirror partners. We
predict configuration mixings for 0+ and 2+ states in 16Ne and
16C. Large isospin symmetry breaking on the level of wave function
component weights is demonstrated for these states and discussed as three-body
mechanism of Thomas-Ehrman shift. It is shown that the description of the
Coulomb displacement energies requires a consistency among three parameters:
the 16Ne decay energy ET, the 15F ground state energy Er, and
the configuration mixing parameters for the 16Ne/16C 0+ and 2+
states. Basing on this analysis we infer the 15F 1/2+ ground state
energy to be Er=1.39−1.42 MeV.Comment: 10 pages 8 figure