***,h2o IP
include procedures
r=1 ang           !set bond distance
theta=104 degree  !set bond angle

basis=vtz         !define basis set

geometry          !geometry input block
o                 !z-matrix
h1,o,r
h2,o,r,h1,theta
endg              !end of geometry input
runmrci           !compute mrci energy of water using defaults
eh2o=energy       !save mrci energy in variable eh2o

set,nelec=9       !set number of electrons to 9
set,symmetry=2    !set wavefunction symmetry to 2
runmrci           !compute mrci energy of h2o+ (2b2 state)

ipci=(energy-eh2o)*toev  !compute mrci ionization potential in ev