# Comment on "Gamma-ray spectra from low-energy positron annihilation processes in molecules"

## TL;DR

This paper critiques a previous study on gamma-ray spectra from positron annihilation in molecules, highlighting errors in their analysis due to neglecting the positron wavefunction's influence.

## Contribution

It clarifies the role of the positron wavefunction in gamma-ray spectra calculations, correcting prior misconceptions in the field.

## Key findings

- Previous conclusions about valence electrons' dominance are incorrect.
- The positron wavefunction significantly affects gamma-ray spectra.
- Proper analysis requires considering the positron wavefunction's effect.

## Abstract

In the article by Ma~\emph{et al.}~[Phys.~Rev.~A {\bf 94}, 052709 (2016)], $\gamma$-ray spectra for positron annihilation on molecules were calculated in the independent-particle approximation with the positron wavefunction set to unity. Based on comparisons with experimental data they concluded that inner valence electrons play a dominant role in positron annihilation. These conclusions are incorrect and resulted from fallacious analysis that ignored the known effect of the positron wavefunction on the spectra.