New relation for nuclear charge radius based on isotope chain

In this paper, experimental values of nuclear charge radii in database published 2013 (CR2013 database) are systematically investigated. We analyze the relationship among three neighboring nuclei based on radius isotope chain database. Then we obtain a new relation for atomic nuclei: given nucleus is equal to average its two nuclei. calculate by combining with CR2013 database, root-mean-squared deviation (RMSD) between our calculated and small: <i>A</i> <inline-formula><tex-math id="M5">\begin{document}$\geqslant$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="15-20212343_M5.jpg"/><graphic xlink:href="15-20212343_M5.png"/></alternatives></inline-formula> 20 (proton number <i>Z</i> id="M6">\begin{document}$\geqslant$\end{document}</tex-math><alternatives><graphic xlink:href="15-20212343_M6.jpg"/><graphic xlink:href="15-20212343_M6.png"/></alternatives></inline-formula> 10 neutron <i>N</i> id="M7">\begin{document}$\geqslant$\end{document}</tex-math><alternatives><graphic xlink:href="15-20212343_M7.jpg"/><graphic xlink:href="15-20212343_M7.png"/></alternatives></inline-formula> 10), RMSD id="M8">\begin{document}$\approx$\end{document}</tex-math><alternatives><graphic xlink:href="15-20212343_M8.jpg"/><graphic xlink:href="15-20212343_M8.png"/></alternatives></inline-formula> 0.00471 fm; id="M9">\begin{document}$\geqslant$\end{document}</tex-math><alternatives><graphic xlink:href="15-20212343_M9.jpg"/><graphic xlink:href="15-20212343_M9.png"/></alternatives></inline-formula> 54, reaches an accuracy id="M10">\begin{document}$\approx$\end{document}</tex-math><alternatives><graphic xlink:href="15-20212343_M10.jpg"/><graphic xlink:href="15-20212343_M10.png"/></alternatives></inline-formula> 0.00337 fm. The systematicness heavy region better than that light region, so more precise region. meantime, also use odd-even staggering improve radius: increases about 6.8%. addition, according CR1999 CR2004 relation, make some predictions radii, find predicted only slightly deviate from difference value measured recent years small. These results show proposed used study feasible accurate. can provide valuable reference future experiments.