$GEN group          (required by MCSCF if CISTEP=GENCI)                         
$CIDET group (required if CITYP=ALDET, ORMAS, or FSOCI)                         
$CIGEN group                  (required if CITYP=GENCI)                         
   This group describes the determinants to be used in a                        
MCSCF or CI wavefunction:                                                       
  a) For full CI calculations (ALDET) the $DET/$CIDET                           
will generate a full list of determinants.  If the CI is                        
part of an MCSCF, this means the MCSCF is of the FORS type                      
(which is also known as CASSCF).                                                
  b) For Occupation Restricted Multiple Active Space                            
(ORMAS) CI, the input in $ORMAS will partition the active                       
orbitals defined here into separate spaces, that is,                            
provide both $DET/$CIDET and $ORMAS.                                            
  c) For Full Second Order CI, provide $CIDET and $SODET                        
  d) For a general CI (meaning user specified space orbital                     
products) provide $DET/$CIDET plus $GEN/$CIGEN and most                         
likely $GCILST (according to the keyword GLIST).                                
In the above, group names for MCSCF/CI jobs are separated                       
by a slash.                                                                     
   Determinants contain several spin states, in contrast                        
to configuration state functions.  The Sz quantum number                        
of each determinant is the same, but the Hamiltonian                            
eigenvectors will have various spins S=Sz, Sz+1, Sz+2, ...                      
so NSTATE may need to account for states of higher spin                         
symmetry.  In Abelian groups, you can specify the exact                         
spatial symmetry you desire.                                                    
GLIST  = general determinant list option                                        
         The keyword GLIST must not be given in a $DET or                       
         $CIDET input group!  These both generate full                          
         determinant lists, automatically.                                      
       = INPUT  means $GCILST input will be read.                               
       = EXTRNL means the list will be read from a disk                         
                file GCILIST generated in an earlier run.                       
       = SACAS  requests generation of sevaral CAS spaces                       
                of different space symmetries, specified by                     
                the input IRREPS.  This option is intended                      
                for state averaged calculations for cases                       
                of high symmetry, where degenerate irreps                       
                of the true group may fall into different                       
                irreps of the Abelian subgroup used.                            
 * * * The next four define the orbital spaces * * *                            
    There is no default for NCORE, NACT, and NELS:                              
NCORE  = total number of orbitals doubly occupied in all                        
NACT   = total number of active orbitals.                                       
NELS   = total number of active electrons.                                      
SZ     = azimuthal spin quantum number for each of the                          
         determinants, two times SZ is therefore the                            
         number of excess alpha spins in each determinant.                      
         The default is SZ=S, extracted from the MULT=2S+1                      
         given in $CONTRL.                                                      
 * * * The following determine the state symmetry * * *                         
GROUP  = name of the point group.  The default is to copy                       
         this from $DATA, if that group is Abelian (C1, Ci,                     
         Cs, C2, C2v, C2h, D2, or D2h).  If not, the point                      
         group used will be C1 (no symmetry).                                   
STSYM =  specifies the spatial symmetry of the state.                           
         Of course these names are the standard group                           
         theory symbols for irreducible representations:                        
              C1   A                                                            
              Ci   Ag  Au                                                       
              Cs   AP  APP   (P stands for prime, i.e. ')                       
              C2   A   B                                                        
              C2v  A1  A2  B1  B2                                               
              C2h  Ag  Bu  Bg  Au                                               
              D2   A   B1  B2  B3                                               
              D2h  Ag  B1g B2g B3g Au  B1u B2u B3u                              
         Default is STSYM being the totally symmetric                           
         state, listed as the first column above.                               
         The free format scanner is not able to read quotes                     
         so the letters "P" must be used in Cs.                                 
IRREPS = specifies the symmetries of the GLIST=SACAS space                      
         determinant list.  This variable should always be                      
         an array, as a single symmetry is more quickly                         
         obtained by the regular full CI code.  The values                      
         given are more primitive than STSYM, being the                         
         following integers, not strings:                                       
         IRREPS=   1   2   3   4   5   6   7   8 meaning                        
              C1   A                                                            
              Ci   Ag  Au                                                       
              Cs   A'  A''                                                      
              C2   A   B                                                        
              C2v  A1  A2  B1  B2                                               
              C2h  Ag  Bu  Bg  Au                                               
              D2   A   B1  B2  B3                                               
              D2h  Ag  B1g B2g B3g Au  B1u B2u B3u                              
 * * * the following control the diagonalization * * *                          
NSTATE = Number of CI states to be found, including the                         
         ground state.  The default is 1, meaning ground                        
         state only.  The maximum number of states is 100.                      
         See also IROOT below (two places).                                     
PRTTOL = Printout tolerance for CI coefficients, the                            
         default is to print any larger than 0.05.                              
ANALYS = a flag to request analysis of the CI energy in                         
         terms of single and double excitation pair                             
         correlation energies.  This is normally used in                        
         CI computations, rather than MCSCF, and when the                       
         wavefunction is dominated by a single reference,                       
         as the analysis is done in terms of excitations                        
         from the determinant with largest CI coefficient.                      
         The defalt is .FALSE.                                                  
ITERMX = Maximum number of Davidson iterations per root.                        
         The default is 100.  A CI calculation will fail                        
         if convergence is not obtained before reaching                         
         the limit.  MCSCF computations will not bomb                           
         if the iteration limit is reached, instead the                         
         last CI vector is used to proceed into the next                        
         orbital update.  In cases with very large active                       
         spaces, it may be faster to input ITERMX=2 or 3                        
         to allow the program to avoid fully converging                         
         the CI eigenvalue problem during the early MCSCF                       
         iterations.  For small active spaces, it is                            
         best to allow the CI step to be fully converged                        
         on every iteration.                                                    
CVGTOL = Convergence criterion for Davidson eigenvector                         
         routine.  This value is proportional to the                            
         accuracy of the coefficients of the eigenvectors                       
         found.  The energy accuracy is proportional to                         
         its square.  The default is 1.0E-5, but 1E-6 if                        
         gradients, MPLEVL, CITYP, or FMO selected).                            
NHGSS  = dimension of the Hamiltonian submatrix which                           
         is diagonalized to obtain the initial guess                            
         eigenvectors.  The determinants forming the                            
         submatrix are chosen on the basis of a low                             
         diagonal energy, or if needed to complete a                            
         spin eigenfunction.  The default is 300.                               
NSTGSS = Number of eigenvectors from the initial guess                          
         Hamiltonian to be included in the Davidson's                           
         iterative scheme.  It is seldom necessary to                           
         include extra states to obtain convergence to                          
         the desired states.  The default equals NSTATE.                        
MXXPAN = Maximum number of expansion basis vectors in the                       
         iterative subspace during the Davidson iterations                      
         before the expansion basis is truncated.  The                          
         default is the larger of 10 or 2*NSTGSS.  Larger                       
         values might help convergence, do not decrease                         
         this parameter below 2*NSTGSS.                                         
CLOBBR = a flag to erase the disk file containing CI                            
         vectors from the previous MCSCF iteration.  The                        
         default is to use these as starting values for                         
         the current iteration's CI.  If you experience                         
         loss of spin symmetry in the CI step, reverse                          
         the default, to always take the CI from the top.                       
         Default = .FALSE.                                                      
 * * * the following control the 1st order density * * *                        
The following pertain to CI calculations by CITYP=xxx (not                      
to the CI step within MCSCF jobs).  Similar keywords apply                      
to MCSCF runs, see just below.                                                  
PURES  = flag to say that IROOT and NGFLGDM just below                          
         should count only those states whose S value is                        
         a match to that implied by MULT in $CONTRL.                            
         Thus, PURES=.TRUE. (the default) allows selection                      
         of S1 as IROOT=2 (the second singlet), even if                         
         there is a T1 state (and maybe others!) between                        
         S0 and S1.  Of course, NSTATE must be large                            
         enough to reach S1 (at least 3, if there is a T1                       
         between S0 and S1).                                                    
         Setting PURES to .FALSE. ignores the spin of each                      
         state when using IROOT and NFLGDM.                                     
IROOT  = the root whose density is saved on the disk file                       
         for subsequent property analysis.  Only one root                       
         can be saved, and the default value of 1 means                         
         the ground state.  Be sure to set NFLGDM to form                       
         the density of the state you are interested in!                        
         IROOT has a similar meaning for MCSCF, see below.                      
NFLGDM = Array controlling each state's density formation.                      
         0 -> do not form density for this state.                               
         1 -> form density and natural orbitals for this                        
              state, print and punch occ.nums. and NOs.                         
         2 -> same as 1, plus print density over MOs.                           
         3 -> same as 2, plus print properties for this                         
              state (see $ELMOM, $ELPOT, et cetera).                            
         The default is NFLGDM(1)=1,0,0,...,0 meaning                           
         only ground state NOs are generated.                                   
SAFLG = is a logical flag that determines whether or not                        
        state averaged CI density matrices and natural                          
        orbitals should be evaluated. Setting SAFLG=.TRUE.                      
        will result in the evaluation of the state averaged                     
        density matrix and NOs.  The default .FALSE. means                      
        generate state-specific densities according to the                      
        NFLGDM input.  See also WSTATE.                                         
WSTATE = An array of up to 100 weights to be given to the                       
         densities of each state in forming the average                         
         density matrix. The default is to optimize a                           
         pure ground state, WSTATE(1)=1.0,0.0,...,0.0.                          
         Note that values given for WSTATE (during a CI                         
         calculation) will only be used if SAFLG=.TRUE.                         
         It should also be noted that any electronic state                      
         that has a nonzero value for WSTATE but a zero                         
         for NFLGDM will reset its value for NFLGDM to 1.                       
FSTATE = An array of up to 100 weights to be given to the                       
         densities of each state in forming the average                         
         density matrix used for QM-EFP polarization.                           
         FSTATE is ignored unless PMTD1=.FALSE. in $CONTRL.                     
         See also PURES.  The default is to set FSTATE from                     
         WSTATE if only the latter is given.                                    
    * * * the following control the state averaged * * *                        
  * * * 1st and 2nd order density matrix computation * * *                      
The following keywords apply to the CI step within the                          
MCSCF iterations.  See just above for similar inputs                            
pertaining to CITYP=xxx calculations.                                           
PURES  = a flag controlling the spin purity of the state                        
         averaging.  If true, the WSTATE array pertains                         
         to the lowest states of the same S value as is                         
         chosen by the MULT keyword in $CONTRL.  In this                        
         case, the value of NSTATE will need to be bigger                       
         than the total number of weights given as WSTATE                       
         if there are other spin states present at low                          
         energies.  If .FALSE., it is possible to state                         
         average over more than one S value, which might                        
         be of interest in spin-orbit coupling jobs.                            
         State-averaged MCSCF gradient runs must use .TRUE.                     
         The default is .TRUE.                                                  
WSTATE = An array of up to 100 weights to be given to the                       
         densities of each state in forming the average.                        
         The default is to optimize a pure ground state,                        
         A small amount of the ground state can help the                        
         convergence of excited states greatly.                                 
         Gradient runs are possible only with pure states.                      
         Be sure to set NSTATE above appropriately!                             
         See also IDWREF just below.                                            
IDWREF = The target state K used to control dynamically                         
         adjusted MCSCF state weights.  This keyword may                        
         only be used for CISTEP=ALDET or CISTEP=ORMAS.                         
         The default is 0, to use static WSTATE values.                         
         Dynamic weights are updated every MCSCF iteration                      
         by the formula:                                                        
            WSTATE(n) = sech^2[-DWPARM*(E(n)-E(K))].                            
         for n= state K and any other weighted states,                          
         followed by a normalization to sum to unity.                           
         The formula gives the largest weight to state K,                       
         with decreasing weight given to states farther                         
         away in energy.  See Deskevich, Nesbitt, and                           
         Werner, J.Chem.Phys. 120, 7281(2004).                                  
         If IDWREF is given, the values given in WSTATE                         
         are used only to specify which roots should have                       
         non-zero weights.                                                      
         The target state is often the ground state, K=1,                       
         but any other state may be used: often K=IROOT!                        
         Converged dynamic weights will be passed to the                        
         determinant MCQDPT program (becoming its default                       
         WPTST) and to the state-averaged gradient/NACME                        
DWPARM = the value of the energy parameter used by IDWREF.                      
         The default is 2.0 eV.                                                 
IROOT  = the MCSCF state whose energy will be used as the                       
         desired value.  (default=0)                                            
         The default means to use the average (according to                     
         WSTATE) of all states as the FINAL energy, which                       
         is not a physically meaningful quantity.                               
         When given as non-zero, IROOT chooses a specific                       
         state, ignoring any states with undesired spins,                       
         see PURES above, and also ignoring any states of                       
         the correct spin which were given no weight.                           
         Any run doing either analytic state-specific                           
         gradients in state-averaged runs, or a gradient by                     
         numerical differentiation must pick the desired                        
         specific IROOT value!                                                  
         IROOT has a similar meaning for CI, see above.                         
FSTATE = An array of up to 100 weights to be given to the                       
         densities of each state in forming the average                         
         density matrix used for QM-EFP polarization.                           
         FSTATE is ignored unless PMTD1=.FALSE. in $CONTRL.                     
         See also PURES.  The default is to set FSTATE from                     
         WSTATE if only the latter is given.                                    

generated on 7/7/2017