Nuclear astrophysics simulations aiming to study the origin of the elements in stars require a multitude of nuclear physics input .
Both systematic model dependent and statistically correlated uncertainties need to be considered .
An application where realistic uncertainty assessments are especially important is the intermediate neutron capture process or i process : a neutron capture regime with neutron densities intermediate between the slow and rapid processes .
Accordingly , the main network flux proceeds on the neutron-rich unstable isotopes up to 4-5 species off the valley of stability .
The i process has been clearly identified to be active in post-AGB stars during the Very Late Thermal Pulse H-ingestion event , and a recent work infers about its important role in early generations of stars .
Here we demonstrate the effect of propagating systematic nuclear uncertainties from different theoretical models to final abundances for a region around the 2 ^ { \mathrm { nd } } peak at A - Z = 80 for elemental ratio predictions involving Ba , La and Eu in i-process conditions .
These elements are used to distinguish different n-capture contributions observed in low-metallicity stars .
For the simple 1-zone model adopted here , predictions vary as much as a factor of 22 in on possible observational plane ( [ La/Eu ] vs. [ Ba/La ] ) .
To consider statistically correlated uncertainties , we similarly perform a full nuclear physics uncertainty study within a given Hauser-Feshbach model and demonstrate the role of correlations on the final stellar abundance uncertainties .
We show that in i-process conditions the main result of neglecting correlations is to underestimate the impact of nuclear uncertainties on the final nucleosynthesis yields by as much as two orders of magnitude .
In the mass region of the neutron shell closure N = 82 Cs final abundances are the most affected by correlated nuclear uncertainties with an uncertainty of about a factor of about 3.5 compared to a factor of 6 \times 10 ^ { -3 } when uncorrelated nuclear uncertainties are used .
In both cases Te and I final abundances shows a negligible effect .