New \textit{ab initio} calculations of the isotopic reactor antineutrino fluxes are provided with exact numerical calculations of the lepton wave functions, assuming all the decay branches are allowed GT transitions. We illustrate that the analytical Fermi function and finite size effect each could have the largest spectral deviation of $\mathcal{O}(10\%)$, whereas the effect of their combination could result in spectral deviations at the level of 5\%---10\%. Meanwhile, we also find that several forms of the extended charge distributions have negligible effects on the spectral variation. Using the state-of-the-art nuclear databases, compared to usual \textit{ab initio} calculations using the analytical single beta decay spectrum, our new calculation shows sizable but opposite spectral deviations at the level of 2\%---4\% for the cumulative antineutrino and electron energy spectra which may partially contribute to the observed spectral excess in the high energy antineutrino range. Finally we observe that the effect of analytical beta decay spectrum approximation is rather universal for all the four fissionable isotopes.

中文翻译：

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具有精确轻子波函数的反应堆反中微子通量的从头算计算

假设所有衰变分支都允许 GT 跃迁，同位素反应堆反中微子通量的新 \textit{ab initio} 计算提供了轻子波函数的精确数值计算。我们说明解析费米函数和有限尺寸效应各自可能具有 $\mathcal{O}(10\%)$ 的最大光谱偏差，而它们的组合的影响可能导致 5\% 水平的光谱偏差---10\%。同时，我们还发现几种形式的扩展电荷分布对光谱变化的影响可以忽略不计。使用最先进的核数据库，与使用分析单β衰变谱的通常 \textit{ab initio} 计算相比，我们的新计算表明，累积反中微子和电子能谱在 2\%---4\% 水平上有相当大但相反的光谱偏差，这可能部分导致在高能反中微子范围内观察到的光谱过剩。最后，我们观察到分析β衰变谱近似的效果对于所有四种可裂变同位素都是相当普遍的。