$EOMINP group
         (optional, for CCTYP=EOM-CCSD, CR-EOM, or CR-EOML)
                   (optional, for CCTYP=EA-EOMx or IP-EOMx)
            (optional for CCSD properties, or CCTYP=CR-CCL)
 
    This group controls the calculation of excited states
by the equation of motion coupled cluster with single and
double excitations, with optional triples corrections.  It
also pertains to electron attachment and detachment
processes, which may result in the system being left in an
excited state.  EOM-CCSD can be selected for RHF or ROHF
reference states, while all other CCTYP listed above can be
used only with SCFTYP=RHF.
 
    These EOM-type runs consist of an SCF calculation on
the reference state, followed by a ground state CCSD (see
the $CCINP input to control the ground state calculation,
and the orbital range correlated), followed by an EOM-CCSD,
IP-EOMCC, or EA-EOMCC calculations on the target states
(see NSTATE below).  In some cases, triples corrections
based on the method of moments approach may follow.
 
    The input group permits selection of how many states
are computed (machine time is linear in the number of
states). Since the target state default is simplistic (only
one excited state in the totally symmetric representation),
it is usually necessary to give this group, to select
NSTATE and IROOT sensibly.
 
    Because this input group is used for several CCTYP
calculations, not all keywords are used in every case, or
the keywords may have slightly different meanings:
a) if the reference type is RHF, and CCTYP is EOM-CCSD, CR-
EOM, or CR-EOML, keywords MULT and NACT are ignored.
b) if the reference type is ROHF, and CCTYP is EOM-CCSD,
keywords CCPRPE, NACT, MTRIP, MEOM, MCI, MINIT, CVGCI,
MAXCI, MICCI are ignored.  MULT is sometimes ignored.
c) if the reference type if RHF, and CCTYP is an ionization
process (EA/IP), keywords CCPRPE, MTRIP, MEOM, MCI, MINIT,
CVGCI, MAXCI, MICCI are ignored.
 
    Additional information on CC and EOM methods can be
found in the "Further Information" section of this manual.
 
 
--- spin and space symmetry, and state selection:
 
MULT   = Spin multiplicities for the target states.
         The meaning depends on the particular calculation.
         The default for cases using $EOMINP's MULT is -1.
         If any doubly excited states or EA/IP quartets
         are sought, be sure to select MINIT=1 so that
         the initial guess states include these.
 
  In case the run is IP-EOM or EA-EOM type, the run will
  pass through open shell code, although the reference
  in $CONTRL must be given as RHF and MULT=1.  The IP or EA
  states will be spin adapted.
   MULT = -1 means target both doublet and quartet states
        =  2 means consider only doublet states
        =  4 means consider only quartet states, which can
             be produced at the EOM-CCSD level by a double
             that unpairs two electrons, and attaches (or
             detaches) a third electron.
 
  In case the run is EOM-CCSD, SCFTYP=ROHF, but $CONTRL
  selects a closed shell reference by MULT=1:
   MULT = -1 means target singlet, triplet, and pentuplets.
        =  1 consider only singlet excited states
        =  3 consider only triplet excited states
        =  5 consider only pentuplet excited states.
 
  In case the run is EOM-CCSD, SCFTYP=ROHF, and $CONTRL
  selects a genuinely open shell reference, the EOM states
  will not be perfectly spin adapted.  The spin projection
  of Ms from $CONTRL's (MULT-1)/2 is the only good quantum
  number.  The excited states will have S values near to
  Ms, Ms+1, or Ms+2 since single and double excitations are
  treated.  Note that target states with spins LOWER than
  Ms are not generated, even if they exist in nature. The
  output will not print approximate S or  values,
  but will label spatial symmetry.
   MULT =  input will be ignored
 
  In case the run is an RHF reference EOM-CCSD (or triples
  correction), the target states are singlets, only.
   MULT =  input will be ignored
 
GROUP     the name of the Abelian group to be used, which
          may be only one of the groups shown in the
          table below. The default is taken from $DATA,
          and is reset to C1 if the group is non-Abelian.
          The purpose is to let the Abelian symmetry be
          turned off by setting GROUP=C1, if desired.
          Symmetry is used to help with the initial
          excited state selection, for controlling
          the EOMCC calculations, and for labeling the
          calculated states in the output (not to speed
          up the calculations).
 
NSTATE    an array of up to 8 integers telling how many
          excited states of each symmetry type should be
          computed. The default is
             NSTATE(1)=1,0,0,0,0,0,0,0
          meaning 1 totally symmetric state is to be found.
          The ground state is always computed, and MUST NOT
          be included in NSTATE's input, for excited state
          runs.  For EA or IP runs, the NSTATE input MUST
          include the target ion's ground state, and may
          include excited states of the ion.
          See also ISELCT below.
 
There is no particular reason the first excited state (or
ionic ground state) should be totally symmetric, so most
runs should give a sensible NSTATE input.  Up to 10 states
can be found in any irrep.  Machine time is linear in the
number of states to be found, so be realistic!
 
NSTATE uses this order for irreducible representations:
       irrep  1    2    3    4    5    6    7    8
         C1   A
         C2   A    B
         Cs   A'   A''
         Ci   Ag   Au
         C2v  A1   A2   B1   B2
         C2h  Ag   Au   Bg   Bu
         D2   A    B1   B2   B3
         D2h  Ag   Au   B1g  B1u  B2g  B2u  B3g  B3u
 
As an aside, NSTATE(1)=0,0,0,0,0,0,0,0 for RHF references
will calculate the ground state only, generating the type
I, II, or possibly III CR-CCSD(T) energies, which aren't
otherwise available in a direct ground state calculation.
 
IROOT     selects the state whose energy is to be saved
          for further calculations, such as numerical
          gradients, or whose properties are evaluated,
          see CCPRPE below.
          The first integer lists the irrep number, from
          the same table as NSTATE, and the second lists
          the number of the state.  Thus, IROOT(1)=3,2
          means the second B1 state, if GROUP=C2V.
          (default IROOT(1)=1,0)
 
IROOT's default is moderately sensible for a RHF-based
excited state run, corresponding to the ground state
(labeled as state 0), as this state must lie in the totally
symmetric representation.  ROHF-based excitations, or EA/IP
runs should select something appropriate!
 
If degenerate EOM-CCSD states are detected, only one such
state will be triples-corrected.  The state chosen for
possible triples will be the lower irrep number, so make
sure IROOT matches this.
 
ISELCT  = an array allowing experts to reduce the number of
          states that are actually solved for.  When given,
          NSTATE determines the number of states generated
          by the initial guess procedures, with ISELECT
          selecting those which carry into the calculation.
          NSTATE(1)=2,2,2,2 with ISELCT(1)=1,3,5,7 prepares
          two guesses in each irrep, but only iterates the
          EOM-CCSD equations for the lowest state in each
          irrep (the guesses are counted serially).
 
     The next two keywords address triples corrections.
     Note that non-iterative triples corrections are not
     presently available for any SCFTYP=ROHF reference.
 
MTRIP     selects the type of noniterative triples
          corrections to SCFTYP=RHF EOM-CCSD energies.
          MINIT applies only to CCTYP=CR-EOM or CR-EOML:
      1 = compute the CR-EOMCCSD(T) triples corrections
          termed type I and II in the output. This is the
          default, which skips the iterative CISD
          calculations needed to construct the
          CR-EOMCCSD(T) triples corrections of type III.
      2 = after performing an additional CISD calculation,
          evaluate all types of the CR-EOMCCSD(T) triples
          corrections, including types I, II, and III.
          This choice of MTRIP uses approximately 50 %
          more memory, but less CPU time than MTRIP=4.
      3 = evaluate the CR-EOMCCSD(T) corrections of type
          III only. As with MTRIP=2, this calculation
          includes the iterative CISD calculation, which
          is needed to construct the type III triples
          corrections, in addition to the EOMCCSD and
          CR-EOMCCSD(T) calculations.
      4 = carry out MTRIP=1 calculations, followed by
          MTRIP=3 calculations, thus evaluating all types
          of the CR-EOMCCSD(T) corrections (types I, II,
          and III in the output). As with MTRIP=2, this
          calculation includes the CISD iterations, which
          are needed to construct the type III triples
          corrections, in addition to the EOMCCSD and
          CR-EOMCCSD(T) calculations.
 
      NACT pertains only to EA-EOM3A or IP-EOM3A runs:
 
NACT   = the number of active MOs used to select the 3p2h
         or 3h2p excitations in EA-EOMCCSDt (EA-EOM3A) or
         IP-EOMCCSDt (IP-EOM3A) calculations.
         For CCTYP=EA-EOM3A, used to describe the (N+1) e-
         system, NACT refers to the NACT lowest unoccupied
         orbitals of the N e- reference system.
         For CCTYP=IP-EOM3A, used to describe the (N-1) e-
         system, NACT refers to the NACT highest occupied
         orbitals of the N e- reference system.
         The default for NACT is 0, which allows no three
         particle or three hole operators, and thus yields
         only EA-EOMCC2 or IP-EOMCC2 results.
         In other words, you should input a value for NACT!
 
CCPRPE = a flag to select computation of the EOM-CCSD level
         excited state density matrices (see also CCPRP in
         $CCINP for ground states).
         The computation takes extra time, to obtain left
         eigenstates, so the default is .FALSE.
 
CCPRPE can be used only if SCFTYP=RHF and CCTYP=EOM-CCSD,
CR-EOM, or CR-EOML.  The property printout includes
transition moments and oscillator strengths between all
pairs of states, as well as the full range of Gaussian
properties (see $ELMOM, etc), for state IROOT only.  CC
density matrices are square, not symmetric, which means
that CCSD natural orbitals come in left/right pairs.  To
minimize the amount of output, only left natural orbitals
for excited state IROOT will be found in the log file.
 
 
--- iterative solver selection:
 
MEOM      selects the solver for the EOMCCSD calculations:
      0 = one EOMCCSD root at a time, united iterative
          space for all calculated roots (default)
      1 = one root at a time, separate iterative space for
          each calculated root
      2 = the Hirao-Nakatsuji multi-root solver
      3 = one root at a time, separate iterative space for
          all computed right/left roots. (compare to 1)
      4 = one root at a time, united iterative spaces
          for each right/left root (compare to 0).
For open shell references, or IP/EA runs, there is only one
EOM-CCSD solver, so MEOM is ignored.
 
MEOM=0,1,2 obtain all the right eigenvectors first, and
then if properties are being computed, proceed to compute
the left eigenvectors.  MEOM=3,4 obtain right and left
eigenvectors simultaneously, and therefore should only be
chosen if you are computing properties (see CCPRP/CCPRPE).
 
MCI       selects the solver for the CISD step, which
          is irrelevant unless MTRIP is bigger than 1.
      1 = one root at a time, separate iterative space for
          each calculated root (default)
      2 = the Hirao-Nakatsuji multi-root solver (slower)
 
 
--- initial guess for EOM-CCSD (and possible CISD) solvers:
 
For both MINIT and MACT below, S and D stand for using all
singles or doubles, while s and d mean restricting those
excitations, both from and to a smaller number of orbitals.
Of course, to define the range of orbitals "active" in the
initial guess, inputs NOACT and NUACT (and perhaps MOACT)
below must be given.  The reason that MINIT=1 is preferred
is that low-lying states with non-negligible double
excitation character, or significant multi-configurational
character are missing in a simple CIS guess, and thus may
not appear in the final converged calculations.
 
MINIT     selects the initial guess procedure for EOM-CCSD,
          and possibly CISD iterations, in case MTRIP>1.
          MINIT applies to all runs reading $EOMINP.
      1 = Use EOMCCSd to start the EOMCCSD iterations,
          and CISd to start possible CISD iterations.
      2 = Use CIS wave functions to start both EOMCCSD,
          or any possible CISD calculations.
  MINIT's default is 2, but MINIT=1 is HIGHLY RECOMMENDED!
 
MACT   = fine tuning of MINIT's EOM-CCSD initial guess
         For MINIT=1 MACT=0, use EOMCCSd guess
         For MINIT=1 MACT=1, use EOMCCsd guess
         For MINIT=2 MACT=0, use CIS guess
         For MINIT=2 MACT=1, use CIs guess
         The default for MACT is 0.
 
MINIT applies to all calculations reading $EOMINP, while
MACT applies only if SCFTYP=ROHF.
 
   the next three define the initial guess active space:
     There are no default values of NOACT and NUACT,
     so the user MUST provide NOACT and NUACT values
     if they are needed.  NOACT and NUACT are usually
     small (5 or so), but should be chosen to avoid
     splitting any degenerate orbital shells.
 
NOACT     the number of occupied MOs in the active space
          for little s or little d initial guesses.
NUACT     the number of unoccupied MOs in the active space
          for little s or little d initial guesses.
MOACT     array allows explicit selection of the active
          orbitals used to define the EOMCCSd and CISd
          initial guesses.  If not provided, the MOACT
          array is filled such that the NOACT highest
          occupied and NUACT lowest unoccupied orbitals
          are selected.  If MOACT is given, the number of
          values provided must be NOACT+NUACT.
          MOACT is most useful in the virtual space, where
          the lowest orbitals might be diffuse in nature.
          An example with 15 occupied orbitals, and where
          the user has searched the virtual space looking
          for valence-like orbitals, might be
               MINIT=1 NOACT=3 NUACT=5
               MOACT(1)=13,14,15, 19,20,24,25,30
 
 
--- iteration control:
 
CVGEOM    convergence criterion on the EOMCCSD excitation
          amplitudes R1 and R2 (default=1.0d-4).
MAXEOM    maximum number of iterations in the EOMCCSD
          calculations (default=50). For MEOM=0 or 1,
          this is the maximum number of iterations per
          each calculated state. For MEOM=2, this is
          the maximum number of iterations for all
          states of the EOMCCSD multi-root procedure.
MICEOM    maximum number of microiterations in the
          EOMCCSD calculations (default=80). Rarely used.
          For MEOM=1 (separate iterative space for each
          root), this is the maximum number of
          microiterations for each calculated state.
          For MEOM=0 or 2 (united iterative space
          for all calculated roots), this is the
          maximum number of microiterations for all
          calculated states. It is much better to
          perform calculations with MICEOM > MAXEOM
          (i.e., in a single iteration cycle). If
          for some reason the EOMCCSD convergence is
          very slow and the iterative space becomes
          very large, it may be worth changing the
          default MICEOM value to MICEOM < MAXEOM
          to reduce the disk usage. This is not
          going to happen too often and normally there
          is no need to change the default MICEOM value.
 
     The next three apply only to closed shell reference
triples, if the triples method MTRIP is greater than 1:
 
CVGCI     convergence criterion for the CISD expansion
          coefficients (default=1.0d-4).
MAXCI     maximum number of iterations in the CISD
          calculation (default=50). For MCI=1, this
          is the maximum number of iterations per each
          calculated CISD state. For MCI=2, this is
          the maximum number of iterations for all
          states of the CISD multi-root procedure.
MICCI     maximum number of microiterations in the
          CISD calculation (default=80). Rarely used.
          For MCI=1 (separate iterative space for each
          root), this is the maximum number of
          microiterations for each calculated state.
          For MCI=2 (united iterative space for all
          calculated roots), this is the maximum
          number of microiterations for all calculated
          states. In analogy to MICEOM, it is much
          better to perform the CISD calculations with
          MICCI > MAXCI (i.e., in a single iteration
          cycle).
 
 
---- restarts:
 
JREST  = 0 this is not a restart
       = 1 restart data is read from AMPROCC file
    One use for this is to request additional states, with
    the restart taking any converged roots from disk, and
    doing an initial guess for additional states.
    You must not change MULT when restarting.
 
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