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Re: Calculation of solvation energy including CAV and DISREP

Alex Granovsky
gran@classic.chem.msu.su


Hi Patrick,

>When ICAV=1 and SOLVENT=WATER, is it necessary to enter the values for TCE, VMOL, STEN, DSTEN and CMF in the input file?

For built-in solvents you do not need to enter anything. According to documentation, the only relevant parameter is:


           If ICAV=1, the following parameter is relevant:

         TABS   = the absolute temperature, in units K.
                  (default=298.0)



>When IDISP=1 and SOLVENT=WATER, is it necessary to enter the values for RHO,N, NT, RDIFF, DK and RW in the input file?


         $DISREP group

            This group controls evaluation of the dispersion and
         repulsion energies by the empirical method of Floris and
         Tomasi.  The group must be given with IDISP=1 in $PCM.
         The two options are controlled by ICLAV and ILJ, only one
         of which should be selected.

         ICLAV = selects Claverie's disp-rep formalism.
               = 0 skip computation.
               = 1 Compute the solute-solvent disp-rep interaction
                   as a sum over atom-atom interactions through a
                   Buckingham-type formula (R^-6 for dispersion,
                   exp for repulsion).  (default)
                   Ref: Pertsin-Kitaigorodsky "The atom-atom
                        potential method", page 146.

         ILJ   = selects a Lennard-Jones formalism.
               = 0 skip computation. (default)
               = 1 solute atom's-solvent molecule interaction is
                   modeled by Lennard-Jones type potentials, R^-6
                   for dispersion, R^-12 for repulsion).

         ---- the following data must given for ICLAV=1:

         RHO   = solvent numeral density
         N     = number of atom types in the solvent molecule
         NT    = an array of the number of atoms of each type in a
                 solvent molecule
         RDIFF = distances between the first atoms of each type
                 and the cavity
         DKT,RWT = parameters of atom-atom interactions (solvent)
         DKA,RWA = parameters of atom-atom interactions (solute)


         The defaults are chosen for water,
            RHO=3.348D-02
            N=2
            NT(1)=2,1
            RDIFF(1)=1.20,1.50
            DKT(1)=1.0,1.36
            RWT(1)=1.2,1.5

         ---- the following data must given for ILJ=1:

         RHO   = solvent numeral density
         EPSI  = an array of energy constants referred to each atom
                 of the solute molecule.
         SIGMA = an array of typical distances, relative to each
                 solute atom

Thus, for water as solvent you need to enter only DKA and RWA arrays.

Hope this helps.

Regards,
Alex Granovsky

On Fri Oct 7 '11 2:56am, Patrick SK Pang wrote
----------------------------------------------
>I used the following input to calculate the solvation energy.
> $CONTRL RUNTYP=Energy $END
> $CONTRL SCFTYP=RHF MAXIT=200 $END
> $CONTRL ICHARG=0  MULT=1 $END
> $SCF DIRSCF=.TRUE. NCONV=9 $END
> $P2P P2P=.T. DLB=.T. $END
> $SYSTEM TIMLIM=3000 MWORDS=100 $END
> $BASIS EXTFIL=.T. GBASIS=cc-pvdz $END
> $PCM SOLVNT=WATER ICAV=1 IDISP=1 $END
> $DISREP ICLAV=1 $END
> $DATA
>Molecule specification

>When ICAV=1 and SOLVENT=WATER, is it necessary to enter the values for TCE, VMOL, STEN, DSTEN and CMF in the input file?

>When IDISP=1 and SOLVENT=WATER, is it necessary to enter the values for RHO,N, NT, RDIFF, DK and RW in the input file?

>I got the zero dispersion free energy and repulsion free energy. Are there any mistakes in the input file?
> � � � � � � ----------------------------------------------
> � � � � � � ------- � RESULTS OF PCM CALCULATION � -------
> � � � � � � ----------------------------------------------

> FREE ENERGY IN SOLVENT = � � � = � �-1917.4382855787 A.U.
> INTERNAL ENERGY IN SOLVENT = � � � = � �-1917.3934872440 A.U.
> DELTA INTERNAL ENERGY = � � � � = � � � �0.0000000000 A.U.
> ELECTROSTATIC INTERACTION = 1/2(PB+PC) + 1/2PX + UNZ= � � � -0.0447983346 A.U.
> PIEROTTI CAVITATION ENERGY � � � � � � � � � � � � �= � � � �0.1118759048 A.U.
> DISPERSION FREE ENERGY � � � � � � � � � � � � � � �= � � � �0.0000000000 A.U.
> REPULSION FREE ENERGY � � � � � � � � � � � � � � � = � � � �0.0000000000 A.U.
> TOTAL INTERACTION (DELTA + ES + CAV + DISP + REP) � = � � � �0.0670775701 A.U.
> TOTAL FREE ENERGY IN SOLVENT � � � � � � � � � � � �= � �-1917.3264096739 A.U.
>


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