Ran across this problem while writing a nuclear decay formula in LibreOffice Writer. Using widevec{~~~~~~~~~} makes the arrow appear stretched. Is there an alternative to widevec, to make an arrow appear lengthened? Here's my current formula:

{}_{88}^{226}"Ra"~~stack{%alpha#widevec{~~~~~~~~~}#4.8"MeV"}~~{}_{86}^{222}"Rn"

Here is how it currently looks and how it is supposed to look like.