# UMRSF-TDDFT single-point excitation energies of butadiene (C4H6)
# BHHLYP / 6-31G*  -- energy only
#
# What makes this "U"MRSF rather than plain MRSF:
#
#    section          keyword        value
#   ----------------------------------------------
#    [input]           runtype       energy
#    [input]           method        tdhf
#    [scf]             type          uhf     <-- UHF reference (the "U")
#    [scf]             multiplicity  3       <-- high-spin (triplet) reference
#    [tdhf]            type          umrsf   <-- unrestricted MRSF response
#    [tdhf]            multiplicity  1       <-- solve singlet target states
#
# UMRSF spin-flips out of a UHF triplet reference. Plain MRSF uses an ROHF
# reference (type=rohf / type=mrsf); everything else is identical.

[input]
system=
 6   -1.901080641    0.114577198    0.000000000
 6   -0.574900598   -0.402237631    0.000000000
 6    1.901080641   -0.114577198    0.000000000
 6    0.574900598    0.402237631    0.000000000
 1   -2.755248674   -0.545115910    0.000000000
 1   -2.071562576    1.183086840    0.000000000
 1    2.755248674    0.545115910    0.000000000
 1   -0.441348756   -1.477941036    0.000000000
 1    2.071562576   -1.183086840    0.000000000
 1    0.441348756    1.477941036    0.000000000
charge=0
runtype=energy
method=tdhf
functional=bhhlyp
basis=6-31g*

[scf]
type=uhf
multiplicity=3

[tdhf]
type=umrsf
nstate=5
multiplicity=1