The high-order deformation effects in even–even \(^{246,248}\) No are investigated by means of pairing self-consistent Woods–Saxon–Strutinsky calculations using the potential-energy-surface (PES) approach in an extended deformation space \((\beta _2, \beta _3,\beta _4,\beta _5,\beta _6,\beta _7, \beta _8)\) . Based on the calculated two-dimensional projected energy maps and different potential energy curves, we found that the highly even-order deformations have an important impact on both the fission trajectory and energy minima, while the odd-order deformations, accompanying the even-order ones, primarily affect the fission path beyond the second barrier. Relative to the light actinide nuclei, the nuclear ground state changes to the superdeformed configuration, but the normally deformed minimum, as the low-energy shape isomer, may still be primarily responsible for enhancing nuclear stability and ensuring experimental accessibility in \(^{246,248}\) No. Our present investigation indicates the nonnegligible impact of high-order deformation effects along the fission valley and will be helpful for deepening the understanding of different deformation effects and deformation couplings in nuclei, especially in this neutron-deficient heavy-mass region.
