  Multi-reference configuration interaction (MRCI) potential energy curves
(PECs) and spin-orbit couplings for the X $^2\Pi$, A $^2 \Sigma^+$, 1 $^2
\Sigma^-$, 1 $^4 \Sigma^-$, and 1 $^4 \Pi$ states of OH are computed and
refined against empirical energy levels and transitions to produce a
spectroscopic model. Predissociation lifetimes are determined by discretising
continuum states in the variational method nuclear motion calculation by
restricting the calculation to finite range of internuclear separations.
Varying this range give a series of avoided crossings between quasi-bound
states associated with the A $^2 \Sigma^+$ and continuum states, from which
predissociation lifetimes are extracted. 424 quasi-bound A $^2 \Sigma^+$ state
rovibronic energy levels are analysed and 374 predissociation lifetimes are
produced, offering good coverage of the predissociation region. Agreement with
measured lifetimes is satisfactory and a majority of computed results were
within experimental uncertainty. A previously unreported A $^2 \Sigma^+$ state
predissociation channel which goes via the X $^2\Pi$ is identified in the
calculations. A python package, binslt, is produced to calculate
predissociation lifetimes, associated line broadening parameters, and
uncertainties from Duo *.states files is made available. The PECs and other
curves from this work will be used to produce a rovibronic ExoMol linelist and
temperature-dependent photodissociation cross sections for the hydroxyl
radical.
