$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. (default=1.10) WB = ionization potential of solvent, in Hartrees. (default=0.451) 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 generated: 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