Although coupled-channels (CC) calculations have been widely used to describe sub-barrier fusion cross sections, theoretical interpretations can be affected by ambiguities arising from the choice of input potential parameters and explicit coupling schemes. In this work, we systematically investigate this “parameter-coupling nonuniqueness” using the ccfull2 code. Starting from the empirical Akyüz–Winther (AW) parametrization, we perform a systematic grid-based scan for several representative heavy-ion systems. The above-barrier fusion cross sections are employed to map an AW-centered Woods–Saxon (WS) parameter space and to select representative phenomenological effective baselines, rather than to determine a unique bare nucleus-nucleus potential. By confronting these effective WS baselines, selected from an AW-centered parameter scan, with various coupling schemes adopted in the literature, we show that for some systems and under some comparison metrics, distinct combinations of potential parameters and coupling schemes can yield phenomenologically similar descriptions of fusion excitation functions. When fusion barrier distributions are further considered, this ambiguity can be more stringently constrained in a system-dependent manner, although not eliminated. Our results emphasize that the barrier distribution provides a more sensitive and complementary observable for testing the consistency of coupling schemes, rather than a unique determination of the coupling effects involved.

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• Low & intermediate energy heavy-ion reactions
• Models & methods for nuclear reactions
• Nuclear fusion
• Nuclear reactions
• Optical, coupled-channel & distorted wave models
• Thermal & statistical models