$GUESS group     (optional, relevant for all SCFTYP's)                          
    This group controls the selection of initial molecular                      
GUESS = Selects type of initial orbital guess.                                  
      = HUCKEL   Carry out an extended Huckel calculation                       
                 using a Huzinaga MINI basis set, and                           
                 project this onto the current basis.                           
                 This is implemented for atoms up to Rn,                        
                 and will work for any all electron or                          
                 core potential basis set.                                      
                 (default for most runs)                                        
      = HCORE    Diagonalize the one electron Hamiltonian                       
                 to obtain the initial guess orbitals.                          
                 This method is applicable to any basis                         
                 set, but does not work as well as the                          
                 HUCKEL guess.                                                  
      = MOREAD   Read in formatted vectors punched by an                        
                 earlier run.  This requires a $VEC deck,                       
                 and you MUST pay attention to NORB below.                      
      = RDMINI   Read in a $VEC deck from a converged SCF                       
                 calculation using GBASIS=MINI, to project                      
                 the MINI orbitals onto the current basis.                      
                 The option improves upon the Huckel guess                      
                 because it involves SCF orbitals, which                        
                 are typically easily obtained in the small                     
                 MINI basis.  This option doesn't work if                       
                 the current basis uses core potentials.                        
                 potentials.  The $VEC from the MINI run                        
                 must contain all virtual orbitals.                             
      = MOSAVED  (default for restarts)  The initial                            
                 orbitals are read from the DICTNRY file                        
                 of the earlier run.                                            
      = SKIP     Bypass initial orbital selection.  The                         
                 initial orbitals and density matrix are                        
                 assumed to be in the DICTNRY file.  Mostly                     
                 used for RUNTYP=HESSIAN when the hessian                       
                 is being read in from the input.                               
The next options are less general, being for Fragment                           
Molecular Orbital runs, or Divide and Conquer runs:                             
      = FMO      Read orbitals from the DICTNRY file, from                      
                 previous FMO run with MODPRP=1.                                
      = HUCSUB   Perform a Huckel guess in each subsystem                       
                 of a Divide and Conquer run                                    
      = DMREAD   Read a density matrix from a formatted $DM                     
                 group, produced by a previous Divide and                       
                 Conquer run, see NDCPRT in $DANDC.                             
    All GUESS types except 'SKIP' permit reordering of the                      
orbitals, carry out an orthonormalization of the orbitals,                      
and generate the correct initial density matrix, for RHF,                       
UHF, ROHF, and GVB, but note that correct computation of                        
the GVB density requires also CICOEF in $SCF.  The density                      
matrix cannot be generated from the orbitals alone for MP2,                     
CI, or MCSCF, so property evaluation for these should be                        
RUNTYP=ENERGY rather than RUNTYP=PROP using GUESS=MOREAD.                       
PRTMO = a flag to control printing of the initial guess.                        
PUNMO = a flag to control punching of the initial guess.                        
MIX    = rotate the alpha and beta HOMO and LUMO orbitals                       
         so as to generate inequivalent alpha and beta                          
         orbital spaces.  This pertains to UHF singlets                         
         only.  This may require use of NOSYM=1 in $CONTRL                      
         depending on your situation.  (default=.FALSE.)                        
NORB   = The number of orbitals to be read in the $VEC                          
         group.  This applies only to GUESS=MOREAD.                             
For -RHF-, -UHF-, -ROHF-, and -GVB-, NORB defaults to the                       
number of occupied orbitals.  NORB must be given for -CI-                       
and -MCSCF-.  For -UHF-, if NORB is not given, only the                         
occupied alpha and beta orbitals should be given, back to                       
back.  Otherwise, both alpha and beta orbitals must                             
consist of NORB vectors.                                                        
NORB may be larger than the number of occupied MOs, if you                      
wish to read in the virtual orbitals.  If NORB is less                          
than the number of atomic orbitals, the remaining orbitals                      
are generated as the orthogonal complement to those read.                       
NORDER = Orbital reordering switch.                                             
       = 0  No reordering (default)                                             
       = 1  Reorder according to IORDER and JORDER.                             
IORDER = Reordering instructions, giving the new molecular                      
         orbital order.  This parameter applies to the                          
         common orbitals (both alpha and beta) except for                       
         UHF, where IORDER only affects the alpha MOs.                          
             Examples (let there be 10 occupied orbitals):                      
               transposition of HOMO and LUMO:                                  
               a different transposition:                                       
                    IORDER(10)=15 IORDER(15)=10                                 
               a more general permutation:                                      
               so the new orbital 10 is the original 9th.                       
         The default is IORDER(i)=i.                                            
JORDER = Reordering instructions.                                               
         Same as IORDER, but for the beta MOs of UHF.                           
INSORB = the first INSORB orbitals specified in the $VEC                        
         group will be inserted into the Huckel guess,                          
         making the guess a hybrid of HUCKEL/MOREAD.  This                      
         keyword is meaningful only when GUESS=HUCKEL, and                      
         it is useful mainly for QM/MM runs where some                          
         orbitals (buffer) are frozen and need to be                            
         transferred to the initial guess vector set,                           
         see $MOFRZ.  (default=0)                                               
  * * * the next are 3 ways to clean up orbitals * * *                          
PURIFY = flag to symmetrize starting orbitals.  This is the                     
         most soundly based of the possible procedures.                         
         However it may fail in complicated groups when the                     
         orbitals are very unsymmetric.  (default=.FALSE.)                      
TOLZ   = level below which MO coefficients will be set                          
         to zero.  (default=1.0E-7)                                             
TOLE   = level at which MO coefficients will be equated.                        
         This is a relative level, coefficients are set                         
         equal if one agrees in magnitude to TOLE times                         
         the other.  (default=5.0E-5)                                           
SYMDEN = project the initial density in order to generate                       
         symmetric orbitals.  This may be useful if the                         
         HUCKEL or HCORE guess types give orbitals of                           
         impure symmetry (?'s present).  The procedure                          
         will generate a fairly high starting energy, and                       
         thus its use may not be a good idea for orbitals                       
         of the quality of MOREAD.  (default=.FALSE.)                           

generated on 7/7/2017