  Calculations from stellar evolutionary models of low- and intermediate-mass
asymptotic giant branch (AGB) stars provide predictions of elemental abundances
and yields for comparison to observations. However, there are many
uncertainties that reduce the accuracy of these predictions. One such
uncertainty involves the treatment of low-temperature molecular opacities that
account for the surface abundance variations of C, N, and O. A number of prior
calculations of intermediate-mass AGB stellar models that incorporate both
efficient third dredge-up and hot bottom burning include a molecular opacity
treatment which does not consider the depletion of C and O due to hot bottom
burning. Here we update the molecular opacity treatment and investigate the
effect of this improvement on calculations of intermediate-mass AGB stellar
models. We perform tests on two masses, 5 M$_{\odot}$ and 6 M$_{\odot}$, and
two metallicities, $Z~=~0.001$ and $Z~=~0.02$, to quantify the variations
between two opacity treatments. We find that several evolutionary properties
(e.g. radius, $T_{\rm eff}$ and $T_{\rm bce}$) are dependent on the opacity
treatment. Larger structural differences occur for the $Z~=~0.001$ models
compared to the $Z~=~0.02$ models indicating that the opacity treatment has a
more significant effect at lower metallicity. As a consequence of the
structural changes, the predictions of isotopic yields are slightly affected
with most isotopes experiencing changes up to 60 per cent for the $Z~=~0.001$
models and 20 per cent for the $Z~=~0.02$ models. Despite this moderate effect,
we conclude that it is more fitting to use variable molecular opacities for
models undergoing hot bottom burning.
