  We introduce state-averaging into the method of Monte Carlo configuration
interaction (SA-MCCI) to allow the stable and efficient calculation of excited
states. We show that excited potential curves for H$_{3}$, including a crossing
with the ground state, can be accurately reproduced using a small fraction of
the FCI space. A recently introduced error measure for potential curves [J. P.
Coe and M. J. Paterson, J. Chem. Phys., 137, 204108 (2012)] is shown to also be
a fair approach when considering potential curves for multiple states. We
demonstrate that potential curves for LiF using SA-MCCI agree well with the FCI
results and the avoided crossing occurs correctly. The seam of conical
intersections for CH$_{2}$ found by Yarkony [J. Chem. Phys., 104, 2932 (1996)]
is used as a test for SA-MCCI and we compare potential curves from SA-MCCI with
FCI results for this system for the first three triplet states. We then
demonstrate the improvement from using SA-MCCI on the dipole of the $2$
$^{1}A_{1}$ state of carbon monoxide. We then look at vertical excitations for
small organic molecules up to the size of butadiene where the SA-MCCI energies
and oscillator strengths are compared with CASPT2 values [M. Schreiber, M. R.
Silva-Junior, S. P. A. Sauer, and W. Thiel, J. Chem. Phys., 128, 134110
(2008)]. We finally see if the SA-MCCI results for these excitation energies
can be improved by using MCCIPT2 with approximate natural orbitals when the PT2
space is not onerously large.
