This study aims at investigating systematically the e®ects of nuclear surface di®useness (NSD) on the alpha decay within the framework of the Coulomb and proximity potential model along with the WKB approximation. We select 300 di®erent parent nuclei in the range Z ¼ 64 106. The proximity potentials Zhang 2013 and Guo 2013 are employed to calculate the nuclear potential. The in°uence of the NSD is applied in the calculations of interaction potential between the emitted alpha particle and daughter nucleus through the reduced radius parameter C . The systematic analysis of the radial behavior of interaction potential with and without the surface di®useness e®ect reveals that these e®ects play decisive role in the calculation of nucleus–nucleus potential at the touching radius of the two interacting nuclei. We indicate that its in°uence decreases outside the touching con¯guration. In addition, our results reveal that the barrier penetration probability of the alpha particle through the barrier decreases by imposing the mentioned physical e®ects. It is worth noting that the calculated -decay half-lives using the Zhang 2013 and Guo 2013 proximity potentials accompanied by the surface e®ects agree very well with the available experimental data. The theoretical half-lives are calculated for 50 superheavy nuclei (SHN) using the modi¯ed forms of the Zhang 2013 and Guo 2013 models. The comparison with available experimental data and also with di®erent empirical formulas demonstrates that the Guo 2013 model is suitable to deal with the alpha-decay half-lives of SHN. Then the predictions of alpha-decay half-lives for 65 SHN with Z ¼ 120 126 are made by using Guo 2013 model with the surface e®ects. We found that there is a good agreement between our predicted half-lives and those obtained from semi-empirical formulas such as Royer and UDL

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