$SVP group                                      (optional)                      
    The presence of this group in the input turns on use of                     
the Surface and Simulation of Volume Polarization for                           
Electrostatics (SS(V)PE) solvation model, or the more exact                     
Surface and Volume Polarization for electrostatics (SVPE)                       
model.  These treat the solvent as a dielectric continuum,                      
and are available with either an isodensity or spherical                        
cavity around the solute.  The solute may be described only                     
by RHF, UHF, ROHF, GVB, or MCSCF wavefunctions.  The energy                     
is reported as a free energy, which includes the factor of                      
1/2 that accounts for the work of solvent polarization                          
assuming linear response.  Gradients are not yet available.                     
    In addition, the CMIRS (Composite Method for Implicit                       
Representation of Solvent) model may be invoked to combine                      
SS(V)PE with the DEFESR (Dispersion, Exchange, and Field-                       
Extremum Short-Range) model to achieve a more complete                          
treatment of solvation.  The field-extremum contribution is                     
designed to describe hydrogen bonding effects.                                  
    The current version 1.0 of CMIRS has parameters for                         
water solvent with isodensity cavities having contours of                       
0.0005, 0.001, or 0.002 au for use with the B3LYP/6-31+G*,                      
B3LYP/G3large, HF/6-31+G*, or HF/G3large electronic                             
structure methods.  In addition, parameters are also                            
available for cyclohexane and benzene solvents with                             
isodensity cavities having contours of 0.0005, 0.001, or                        
0.002 au for use with the B3LYP/6-31+G* method.                                 
     Typical use of these methods will involve a prior step                     
to do an equivalent calculation on the given solute in the                      
gas phase.  This provides a set of orbitals that can be                         
used as a good initial guess for the subsequent run                             
including solvent.  It also provides the gas phase energy                       
(input as keyword EGAS) that can be subtracted from the                         
energy in solvent to obtain the free energy of solvation.                       
     Many runs will be fine with all parameters set at                          
their default values. The most important parameters a user                      
may want to consider changing are:                                              
NVLPL  = treatment of volume polarization                                       
         0 - SS(V)PE method, which simulates volume                             
             polarization by effectively folding in an                          
             additional surface polarization (default)                          
         N - SVPE method, which explicitly treats volume                        
             polarization with N extra layers                                   
DIELST = static dielectric constant of solvent                                  
          (default = 78.39, appropriate for water)                              
IVERT  = 0 do an equilibrium calculation (default)                              
         1 do a nonequilibrium calculation to get the final                     
           state of a vertical excitation - this requires                       
           that IRDRF=1 to read the $SVPIRF input group                         
           that was punched with IPNRF=1 in a run on the                        
           initial state - note that a meaningful result is                     
           obtained only if the initial and final states                        
           both come from the same wavefunction/basis set/                      
           geometry/solvation model.                                            
DIELOP = optical dielectric constant of solvent -                               
         this only relevant if IVERT=1                                          
         (default 1.776, appropriate for water)                                 
EGAS   = gas phase energy (optional): if given, the program                     
         will output the free energy of solvation and the                       
         change in solute internal energy due to solvation.                     
         Note that a meaningful result is obtained only if                      
         EGAS comes from the same wavefunction/basis set/                       
         geometry as is used in the solvation calculation                       
ISHAPE = sets the shape of the cavity surface                                   
         0 - electronic isodensity surface (default)                            
         1 - spherical surface                                                  
RHOISO = value of the electronic isodensity contour used to                     
          specify the cavity surface, in electrons/bohr**3                      
          (relevant if ISHAPE=0; default=0.001)                                 
RADSPH = sphere radius used to specify the cavity surface.                      
         A positive value means it is given in Bohr,                            
         negative means Angstroms. (relevant if ISHAPE=1;                       
         default is half the distance between the                               
         outermost atoms plus 1.4 Angstroms)                                    
INTCAV = selects the surface integration method                                 
         0 - single center Lebedev integration (default)                        
         1 - single center spherical polar integration,                         
             not recommended; Lebedev is far more efficient                     
NPTLEB = number of Lebedev-type points used for single                          
         center surface integration. The default value                          
         has been found adequate to obtain the energy to                        
         within 0.1 kcal/mol for solutes the size of                            
         monosubstituted benzenes. (relevant if INTCAV=0)                       
         Valid choices are 6, 14, 26, 38, 50, 86, 110, 146,                     
         170, 194, 302, 350, 434, 590, 770, 974, 1202,                          
         1454, 1730, 2030, 2354, 2702, 3074, 3470, 3890,                        
         4334, 4802, 5294, or 5810. (default=1202)                              
NPTTHE, NPTPHI = number of (theta,phi) points used for                          
         single center surface integration. These should                        
         be multiples of 2 and 4, respectively, to provide                      
         symmetry sufficient for all Abelian point groups.                      
         (relevant if INTCAV=1; defaults = 8,16; these                          
         defaults are probably too small for all but the                        
         tiniest and simplest of solutes.)                                      
TOLCHG = a convergence criterion on the program variable                        
         named CHGDIF, which is the maximum change in any                       
         surface charge from its value in the previous                          
         iteration (default=1.0D-6). This is checked in                         
         each SCF iteration, although the actual value                          
         is not printed until final convergence is reached.                     
The single-center surface integration approach may fail for                     
certain highly nonspherical molecular surfaces. The program                     
will automatically check for this and bomb out with a                           
warning message if need be. The single-center approach                          
succeeds only for what is called a star surface, meaning                        
that an observer sitting at the center has an unobstructed                      
view of the entire surface. Said another way, for a star                        
surface any ray emanating out from the center will pass                         
through the surface only once. Some cases of failure may be                     
fixed by simply moving to a new center with the ITRNGR                          
parameter described below. But some surfaces are inherently                     
nonstar surfaces and cannot be treated with this program                        
until more sophisticated surface integration approaches are                     
ITRNGR = translation of cavity surface integration grid                         
         0 - no translation (i.e., center the grid at the                       
             origin of the atomic coordinates)                                  
         1 - translate to center of nuclear mass                                
         2 - translate to center of nucl. charge (default)                      
         3 - translate to midpoint of outermost atoms                           
         4 - translate to midpoint of outermost                                 
             non-Hydrogen atoms                                                 
         5 - translate to user-specified coordinates,                           
             in Bohr                                                            
         6 - translate to user-specified coordinates,                           
             in Angstroms                                                       
TRANX, TRANY, TRANZ = x,y,z coordinates of translated                           
         cavity center, relevant if ITRNGR=5 or 6.                              
         (default = 0,0,0)                                                      
IROTGR = rotation of cavity surface integration grid                            
         0 - no rotation                                                        
         1 - rotate initial xyz axes of integration grid to                     
             coincide with principal moments of nuclear                         
             inertia (relevant if ITRNGR=1)                                     
         2 - rotate initial xyz axes of integration grid to                     
             coincide with principal moments of nuclear                         
             charge (relevant if ITRNGR=2; default)                             
         3 - rotate initial xyz axes of integration grid                        
             through user-specified Euler angles as defined                     
             by Wilson, Decius, Cross                                           
ROTTHE, ROTPHI, ROTCHI = Euler angles (theta, phi, chi) in                      
             degrees for rotation of the cavity surface                         
             integration grid, relevant if IROTGR=3.                            
IOPPRD = choice of the system operator form. The default                        
         symmetric form is usually the most efficient, but                      
         when the number of surface points N is big it can                      
         require very large memory (to hold two N by N                          
         matrices). The nonsymmetric form requires solution                     
         of two consecutive system equations, and so is                         
         usually slower, but as trade-off requires less                         
         memory (to hold just one N by N matrix). The two                       
         forms will lead to slightly different numerical                        
         results, although tests documented in the third                        
         reference given in Further Information show that                       
         the differences are generally less than the                            
         inherent discretization error itself and so are                        
         not meaningful.                                                        
         0 - symmetric form (default)                                           
         1 - nonsymmetric form                                                  
                        * * *                                                   
    The CMIRS (Composite Method for Implicit Representation                     
of Solvent) model is a combination of SS(V)PE with the                          
DEFESR (Dispersion, Exchange, and Field-Extremum Short-                         
Range) model.  It borrows use of a grid from the DFT code,                      
and therefore is currently implemented only for the $DFT                        
METHOD=GRID choice in $CONTRL: note that HF calculations                        
can be done with DFTTYP=HFX in $CONTRL.  If default                             
parameters are desired (which correspond to water solvent,                      
an isodensity cavity with contour 0.001 au, and the                             
B3LYP/6-31+G* electronic structure method), then only the                       
IDEF flag needs to be set.                                                      
IDEF     = flag to activate DEFESR calculations                                 
           0 - DEFESR energies are not computed (default)                       
           1 - DEFESR energies are also computed                                
RHOSOLV  = average electron density of solvent for use in                       
           the dispersion model (default=0.05 au for water)                     
DISDMP   = dispersion damping factor (default 7.0 bohr).                        
           This value has been found to be nearly optimal                       
           for all solvent/cavity/methods tested.                               
DISLIN   = dispersion linear parameter                                          
           (default=0.0109369 au).                                              
           It is sensitive to the solvent/cavity/method.                        
EXCLIN   = exchange linear parameter                                            
           (default=0.0460402 au).                                              
           It is sensitive to the solvent/cavity/method.                        
NGSLGR   = order of Gauss-Laguerre numerical integration                        
           used for the exchange term (default=6).                              
           Possible values are 1 to 25.                                         
FNNL,FPNL = field-negative and field-positive nonlinear                         
           parameters (default=3.6 and 3.6).  These values                      
           have been found to be nearly optimal for all                         
           solvent/cavity/methods tested.                                       
FNLIN,FPLIN = field-negative and field-positive linear                          
           parameters (defaults=-945.810 and -17.8279 au).                      
           They are sensitive to the solvent/cavity/method.                     
           For solvents like cyclohexane and benzene that                       
           have negligible hydrogen-bonding capability they                     
           can be set to 0.                                                     
SMVLE  = flag to turn on an alternative (to DEFESR) semi-                       
         empirical correction for local electrostatic                           
         effects based on the electric field's normals to                       
         the surface cavity.  This also adds cavitation/                        
         dispersion/solvent structure (CDS) effects drawn                       
         from the SMD model, see SMD in $PCM.                                   
                        * * *                                                   
     The remaining parameters below are rather specialized                      
and rarely of concern.  They should be changed from their                       
default values only for good reason by a knowledgeable                          
TOLCAV = convergence criterion on maximum deviation of                          
         calculated vs. requested RHOISO                                        
         (relevant if ISHAPE=0; default=1.0D-10)                                
ITRCAV = maximum number of iterations to allow before                           
         giving up in search for isodensity surface.                            
         (relevant if ISHAPE=0; default=99)                                     
NDRCAV = highest analytic density derivative to use in the                      
         search for isodensity surface.                                         
         0 - none, use finite differences (default)                             
         1 - use analytic first derivatives                                     
LINEQ  = selects the solver for the linear equations                            
         that determine the effective point charges on                          
         the cavity surface.                                                    
         0 - use LU decomposition in memory if space                            
             permits, else switch to LINEQ=2                                    
         1 - use conjugate gradient iterations in memory if                     
             space permits, else use LINEQ=2 (default)                          
         2 - use conjugate gradient iterations with the                         
             system matrix stored externally on disk.                           
CVGLIN = convergence criterion for solving linear equations                     
         by the conjugate gradient iterative method                             
         (relevant if LINEQ=1 or 2; default = 1.0D-7)                           
CSDIAG = a factor to multiply diagonal elements to improve                      
         the surface potential matrix, S.                                       
         (default = 1.104, optimal for Lebedev integration)                     
IRDRF  = a flag to read in a set of point charges as an                         
         initial guess to the reaction field.                                   
         0 - no initial guess reaction field (default)                          
         1 - read point charges from $SVPIRF input group.                       
             It is up to the user to be sure that the                           
             number of charges read is appropriate.                             
IPNRF  = a flag to punch the final reaction field.                              
         0 - no punch (default)                                                 
         1 - punch in format of $SVPIRF input group                             

generated on 7/7/2017