In version 14.2, the outputs of IsotopeData that produce fractional answers (e.g., isotope abundances, decay branching ratios), have suffered a change in format (compared to version 13.2). The new format not only is less convenient, but also appears to cause a loss in precision.

For example, in version 13.2, the isotope abundances of lithium-6 and lithium-7 print as 0.0759 and 0.9241, respectively. The abundances of all other lithium isotopes output 0. (with a decimal point). These values agree with other databases.

In version 14.2, the isotope abundances of lithium-6 and lithium-7 print as 0. % (with a red square outline) and 1. x 10^2 %. The abundances of the other lithium isotopes are printed as 0%, without the decimal point or a red outline.

This suggests there has been some rounding that caused some values to lose all precision. It is also worth noting that the version 13.2 outputs, with the simple fractions, were more convenient for calculations.

There is a way to recover something similar to the outputs of version 13.2 in version 14.2, and that is to add 0.0 to the result.

With this trick, in version 14.2, the isotope abundances of lithium-6 and lithium-7 print as 0.0485 and 0.9515, respectively (no more percentages). While these values add to 1, as they should, they are different from the values obtained in version 13.2.

It is possible that these differences are the result of an update of our knowledge of the abundances of the lithium isotopes, but, to my knowledge, other databases have not changed their values. It seems to me that this is the result of an unsuccessful attempt to standardize the reported precision of these data.

There are many similar fractional outputs in this database that are close to zero (many isotopes are extremely rare, so that their abundances will be close to zero, and many others have decay modes that occur extremely seldom, causing very small branching ratios). The concern is that all these outputs will lose accuracy and be reported as zero, and a simple attempt to recover these values seems to lead to incorrect outputs.

Does anybody have an explanation for this? Is this just a bug? Is there a way to control this behavior with some precision or formatting option?

Thanks in advance for your time, Otto Linsuaín

P.S. The outputs mentioned above can be obtained with commands like: IsotopeData["Lithium6","IsotopeAbundance"]

For the branching ratios one should use an unstable isotope, for example: IsotopeData["Neptunium239","BranchingRatios"]