$PCM group                                   (optional)                         
   This group controls solvent effect computations using                        
the Polarizable Continuum Model.  If this group is found in                     
the input file, a PCM computation is performed.  The                            
default calculation, chosen by selecting only the SOLVNT                        
keyword, is to compute the electrostatic free energy.                           
Appropriate numerical constants are provided for a wide                         
range of solvents.  Typical input might be as simple as                         
 $PCM SOLVNT=H2O $END                                                           
There is in fact little need to give other PCM input data,                      
except perhaps atomic radii in $PCMCAV if your molecule                         
contains an unusual atom.                                                       
   Additional keywords (ICOMP, ICAV, IDISP, or IREP/IDP)                        
allow for more sophisticated computations, namely                               
cavitation, repulsion, and dispersion free energies.  The                       
methodology for these is general, but numerical constants                       
are provided only for water.                                                    
   Alternatively, the PCM codes for electrostatics can be                       
combined with U. Minnesota codes to implement the SMD                           
solvation model.  SMD combines the electrostatics with an                       
alternative cavitation, dispersion, and solute structure                        
reorganization (CDS) correction.  Since SMD also changes                        
the atomic radii, the electrostatics interaction is                             
changed.  See keyword SMD below (and the 4th chapter of                         
this manual).                                                                   
   Calculations are possible on either a solute embedded in                     
a PCM continuum, or a system combining a solute & EFP                           
explicit solvent molecules, embedded in a PCM continuum.                        
The energy and/or nuclear gradients are programmed for RHF,                     
ROHF, UHF, GVB, and MCSCF wavefunctions, and for DFT or MP2                     
level calculations using RHF, ROHF, and UHF.  Closed shell                      
TD-DFT excited states have analytic gradients, as well.                         
Polarizabilities in solution may be found by RUNTYP=TDHF.                       
Parallel computation is enabled, with scaling similar to                        
the scaling of the corresponding gas phase calculation.                         
PCM is not programmed for CI or Coupled Cluster.  PCM is                        
enabled for use during semiempirical MOPAC runs.                                
   See the Fragment Molecular Orbital section of the                            
References chapter for information on using PCM within the                      
FMO model.                                                                      
   There is additional information on PCM in the References                     
chapter of this manual.  This includes information on which                     
keyword combinations were default values in the past.                           
IEF      switch to choose the type of PCM model used.                           
         The default is -10, iterative C-PCM.                                   
      =  0 isotropic dielectrics using the original                             
           formulation of PCM for dielectrics (D-PCM)                           
      =  1 anisotropic dielectric using the Integral                            
           Equation Formalism (IEF) of PCM, see $IEFPCM                         
      =  2 ionic solutions using IEF-PCM, see $IEFPCM                           
      =  3 isotropic dielectrics using IEF-PCM with matrix                      
           inversion solver, see $IEFPCM                                        
      = -3 isotropic dielectric IEF-PCM with iterative                          
           solver, see $PCMITR.                                                 
      = 10 conductor-like PCM (C-PCM) with matrix                               
           inversion.  Charge scaling is (Eps-1.0)/Eps                          
      =-10 C-PCM, with iterative solver. See $PCMITR.                           
      = 9,11,13 IEF-PCM for certain non-standard                                
           environment. (See $REORG input for details)                          
      = 14 also models isotropic dielectric like IEF=3 but                      
           uses a slightly different implementation of IEF                      
           equations (See $REORG input for further details)                     
C-PCM is normally a better choice than IEF-PCM.  The                            
iterative solvers chosen by IEF=-3 or -10 usually reproduce                     
the energy of the explicit solvers IEF=3 or 10 to within                        
1.0d-8 Hartrees, and will be much faster and use less                           
memory for large molecules.  D-PCM should be considered                         
obsolete, and choices 1 and 2 are seldom made.                                  
                           * * *                                                
SOLVNT = keyword naming the solvent, whose choices depend                       
         on use of non-SMD or SMD models.  For the former,                      
         the eight numerical constants defining the solvent                     
         are internally stored for:                                             
             WATER (or H2O)                                                     
             CH3OH                    C2H5OH                                    
             CLFORM (or CHCl3)        CTCL (or CCl4)                            
             METHYCL (or CH2Cl2)      12DCLET (or C2H4Cl2)                      
             BENZENE (or C6H6)        TOLUENE (or C6H5CH3)                      
             CLBENZ (or C6H5Cl)       NITMET (or CH3NO2)                        
             NEPTANE (or C7H16)       CYCHEX (or C6H12)                         
             ANILINE (or C6H5NH2)     ACETONE (or CH3COCH3)                     
             THF                      DMSO (or DMETSOX)                         
         SMD has many additional solvents, see below.                           
The default solvent name is "INPUT" which means you must                        
give the numerical values defining some other solvent, as                       
described below.                                                                
           * * * non-SMD calculations * * *                                     
The next set of parameters controls the computation:                            
parameterization of the solvents, ICOMP which has an impact                     
on the PCM electrostatics, and other keywords related to                        
cavitation, dispersion, and repulsion corrections: ICAV,                        
IDISP, IREP/IDP.                                                                
ICOMP  = Compensation procedure for induced charges.                            
         Gradient runs require ICOMP be 0 or 2 only.                            
       = 0 None. (default)                                                      
       = 1 Yes, each charge is corrected in proportion                          
           to the area of the tessera to which it belongs.                      
       = 2 Yes, using the same factor for all tesserae.                         
       = 3 Yes, with explicit consideration of the                              
           portion of solute electronic charge outside                          
           the cavity, by the method of Mennucci and                            
           Tomasi.  See $NEWCAV.                                                
Technical issues are: IEF=0 should normally choose ICOMP=2.                     
Options IEF=1 or 2 are incompatible with gradients and must                     
choose ICOMP=0, and presently contain bugs (do not choose                       
these!).  IEF=3 may not choose ICOMP=3, but if diffuse                          
basis functions are in use, it may benefit from ICOMP=2.                        
ICAV   = calculate the cavitation energy, by the method of                      
         Pierotti and Claverie.  The cavitation energy is                       
         computed at the end of the run (e.g. at the final                      
         geometry) as an additive constant to the energy.                       
       = 0 skip the computation (default)                                       
       = 1 perform the computation.                                             
  If ICAV=1, the following parameter is relevant:                               
TABS   = the temperature, in Kelvin. (default=298.0)                            
     There are two procedures for the calculation of the                        
repulsion and dispersion contributions to the free energy.                      
Parameterizations were obtained for RHF cases, so the                           
implementation permits their use only for RHF.                                  
IDISP is older, and is incompatible with IREP and/or IDP.                       
Nuclear gradients are available for IDISP (select either                        
ICLAV or ILJ in $DISREP).  The older GEPOL-GB tessellation                      
does some gradient terms numerically, which results in a                        
less accurate gradient.                                                         
IDISP  = Calculation of both dispersion and repulsion                           
         free energy through the empirical method of                            
         Floris and Tomasi.                                                     
       = 0 skip the computation (default)                                       
       = 1 perform the computation.  See $DISREP.                               
The next two options add repulsive and dispersive terms to                      
the solute hamiltonian, in a more ab initio manner, by the                      
method of Amovilli and Mennucci.  These may be used only in                     
single point energy calculations (see IDISP if you wish to                      
use gradients).                                                                 
IREP   = Calculation of repulsion free energy                                   
       = 0 skip the computation (default)                                       
       = 1 perform the computation.  See $NEWCAV.                               
IDP    = Calculation of dispersion free energy                                  
       = 0 skip the computation (default)                                       
       = 1 perform the computation.  See $DISBS.                                
  If IDP=1, then three additional parameters must be                            
  defined.  The two solvent values correspond to water,                         
  and therefore these must be input for other solvents.                         
WA     = solute average transition energy.  This is                             
         computed from the orbital energies for RHF,                            
         but must be input for MCSCF runs.                                      
WB     = ionization potential of solvent, in Hartrees.                          
ETA2   = square of the zero frequency refractive index                          
         of the solvent.  (default=1.75)                                        
--- the next 8 values define the solvent, if SOLVNT=INPUT:                      
RSOLV  = the solvent radius, in units Angstrom                                  
EPS    = the dielectric constant                                                
EPSINF = the dielectric constant at infinite frequency.                         
         This value must be given only for RUNTYP=TDHF,                         
         if the external field frequency is in the optical                      
         range and the solvent is polar; in this case the                       
         solvent response is described by the electronic                        
         part of its polarization.  Hence the value of the                      
         dielectric constant to be used is that evaluated                       
         at infinite frequency, not the static one (EPS).                       
         This value also must be given for TD-DFT/PCM,                          
         when NONEQ is selected in $TDDFT.                                      
         For nonpolar solvents, the difference between                          
         the two is almost negligible.                                          
TCE    = the thermal expansion coefficient, in units 1/K                        
VMOL   = the molar volume, in units ml/mol                                      
STEN   = the surface tension, in units dyne/cm                                  
DSTEN  = the thermal coefficient of log(STEN)                                   
CMF    = the cavity microscopic coefficient                                     
Values for TCE, VMOL, STEN, DSTEN, CMF need to be given                         
only for the case ICAV=1.  Input of any or all of these                         
values will override an internally stored value, if you                         
have chosen a solvent by its name.                                              
              * * * SMD calculations * * *                                      
The Solvation Model Density (SMD) uses the solute's quantum                     
mechanical density (the D in the model's name) for IEF-PCM                      
or C-PCM's electrostatics.  It adds "CDS" corrections for                       
cavitation, dispersion, and solvent structure, all of which                     
have nuclear gradient contributions coded.  The SMD model's                     
parameters were developed using IEF-PCM and GEPOL cavity                        
construction, but SMD may also be used with the more robust                     
C-PCM model and FIXPVA cavity tessellation.                                     
SMD    = a flag to select "Solvation Model Density".                            
         default=.FALSE.  If chosen, naming the solvent                         
         by SOLVNT=xxx picks numerical values for the                           
         six SOLX keywords just below, which may then be                        
         omitted.  The SMD model knows 178 solvents, see                        
         chapter 4 of this manual for a listing.                                
SOLA   = Abraham's hydrogen bond acidity                                        
SOLB   = Abraham's hydrogen bond basicity                                       
SOLC   = aromaticity: fraction of non-H solvent atoms                           
         which are aromatic Carbon atoms                                        
SOLG   = macroscopic surface tension at the air/solvent                         
         interface, in units of cal/mole/angstrom**2                            
SOLH   = halogenicity: fraction of non-H solvent atoms                          
         which are F, Cl, or Br                                                 
SOLN   = index of refraction at optical frequencies at                          
         298K, n-sub-20-super-D.                                                
In addition to the parameters just above, SMD provides its                      
own set of radii for each atom's sphere, so $PCMCAV input                       
must not be given.  Of course, if you choose SMD=.TRUE.,                        
with its built in CDS correction, you must select                               
ICOMP=ICAV=IDISP=IREP=IDP=0!  See also SMVLE in $SVP.                           
                         * * *                                                  
--- interface to Fragment Molecular Orbital method:                             
IFMO     specifies "n" for the n-body FMO expansion of the                      
         total electron density to be used in PCM.                              
         Default=0 should be used for any non-FMO run.                          
         Non-zero IFMO can be used only within the regular                      
         FMO framework (q.v. for further FMO limitations):                      
         IFMO should be less or equal than NBODY in $FMO,                       
         Not all PCM options can be used with FMO!                              
         The following are explicitly permitted:                                
            IEF=-3,-10; ICOMP=0,1,2; MTHALL=2,4;                                
            IDISP=0,1; IDP=0; IREP=0,1.                                         
            Gradient runs require ICOMP=0.                                      
         IFMO may take the values of -1,0,1,2,3.                                
         For FMO, IFMO=-1 chooses PCM<1>,                                       
                  IFMO= 1 chooses PCM[1],                                       
                  IFMO= 2, NPCMIT=2 chooses PCM[1(2)],                          
                  IFMO= 2, NPCMIT>2 chooses PCM[2],                             
                  IFMO= 3, NPCMIT=2 chooses PCM[1(3)],                          
                  IFMO= 3, NPCMIT>2 chooses PCM[3].                             
         The fully analytic gradient requires IFMO=-1 or 1.                     
--- the next set of keywords defines the molecular cavity,                      
used for electrostatic (surface charge) calculations.  See                      
also $PCMCAV, $TESCAV, and $NEWCAV for other cavities.                          
NESFP  =   option for spheres forming the cavity:                               
       = 0 centers spheres on each nucleus in the quantum                       
           solute, and every atom in EFP.  (default)                            
       = N use N initial sphere, whose centers XE, YE, ZE                       
           and radii RIN must be specified in $PCMCAV.                          
   The cavity generation algorithm may use additional                           
spheres to smooth out sharp grooves, etc. If you are                            
interested in smoother cavities, see the SVPE and SS(V)PE                       
methods, which use a cavity based on isodensity surfaces.                       
The following parameters control how many extra spheres are                     
OMEGA and FRO = GEPOL parameters for the creation of the                        
         'added spheres' defining the solvent accessible                        
         surface. When an excessive number of spheres is                        
         created, which may cause problems of convergence,                      
         the value of OMEGA and/or FRO must be increased.                       
         For example, OMEGA from 40 to 50 ... up to 90,                         
                      FRO from 0.2 ... up to 0.7.                               
         (defaults are OMEGA=40.0, FRO=0.7)                                     
RET    = minimum radius (in A) of the added spheres.                            
         Increasing RET decreases the number of added                           
         spheres.  A value of 100.0 (default) inhibits the                      
         addition of any spheres, while 0.2 fills in many.                      
         The use of added spheres is strongly discouraged.                      
MODPAR = cavity generation's parallelization option:                            
         0 parallelize tessellation, 1= do not parallelize.                     
         The present parallel code is inefficient, so                           
         MODPAR=0 is recommended.  (default=0)                                  
         Don't confuse this with running PCM in parallel!                       
MXSP   = the maximum number of spheres.                                         
         Default: MXATM parameter in GAMESS.                                    
MXTS   = the maximum number of tesserae.                                        
         Default: Nsph*NTSALL*2/3, where Nsph is the number                     
         of spheres (usually equal to the number of atoms).                     
         If less than 20 spheres are present, default is                        
         Nsph*NTSALL. For GEPOL-RT, NTSALL=960 is used in                       
         setting the default value.                                             
         Note on MXSP and MXTS: PCM usually constructs                          
         more than one cavity (for example, a different one                     
         for the cavitation energy).  MXSP and MXTS must be                     
         large enough to handle every possible cavity.                          
--- arcane parameters:                                                          
IPRINT = 0 normal printing (default)                                            
       = 1 turns on debugging printout                                          
IFIELD = At the end of a run, calculate the electric                            
         potential and electric field generated by the                          
         apparent surface charges.                                              
       = 0 skip the computation (default)                                       
       = 1 on nuclei                                                            
       = 2 on a planar grid                                                     
  If IFIELD=2, the following data must be input:                                
AXYZ,BXYZ,CXYZ = each defines three components of the                           
                 vertices of the plane where the reaction                       
                 field is to be computed (in Angstroms)                         
      A ===> higher left corner of the grid                                     
      B ===> lower left corner of the grid                                      
      C ===> higher right corner of the grid                                    
NAB = vertical subdivision (A--B edge) of the grid                              
NAC = horizontal subdivision (A--C edge) of the grid.                           

generated on 7/7/2017