  We present an ab initio study of the rovibronic spectra of sulfur monoxide
($^{32}$S$^{16}$O) using internally contracted multireference confoguration
interaction (ic-MRCI) method and aug-cc-pV5Z basis sets. It covers 13
electronic states $X^{3}\Sigma^{-}$, $a^{1}\Delta$, $b^{1}\Sigma^{+}$,
$c^{1}\Sigma^{-}$, $A^{\prime\prime 3}\Sigma^{+}$, $A^{\prime 3}\Delta$,
$A^{3}\Pi$, $B^{3}\Sigma^{-}$, $C^{3}\Pi$, $d^{1}\Pi$, $e^{1}\Pi$, $C^{\prime
3}\Pi$, and $(3)^{1}\Pi$ ranging up to 66800 cm$^{-1}$. The ab initio
spectroscopic model includes 13 potential energy curves, 23 dipole and
transition dipole moment curves, 23 spin-orbit curves, and 14 electronic
angular momentum curves. A diabatic representation is built by removing the
avoided crossings between the spatially degenerate pairs $C^{3}\Pi - C^{\prime
3}\Pi$ and $e^{1}\Pi - (3)^{1}\Pi$ through a property-based diabatisation
method. We also present non-adiabatic couplings and diabatic couplings for
these avoided crossing systems. All phases for our coupling curves are defined,
and consistent, providing the first fully reproducible spectroscopic model of
SO covering the wavelength range longer than 147 nm. Finally, an ab initio
rovibronic spectrum of SO is computed.
