Keywords for COSMO

The Conductor-like Screening Model (cosmo) is a continuum solvation model, where the solute molecule forms a cavity within the dielectric continuum of permittivity epsilon that represents the solvent. A brief description of the method is given in chapter 14. The model is currently implemented for SCF energy and gradient calculations (dscf/ridft and grad/rdgrad), MP2 energy calculations (RIMP2 and mpgrad) and MP2 gradients (RIMP2).

For simple HF or DFT single point calculations or optimizations with standard settings, we recommend to add the $cosmo keyword to the control file and to skip the rest of this section.

Please note: due to improvements in the $\bf A$ matrix and cavity setup the cosmo energies and gradients may differ from older versions (5.7 and older). The use_old_amat option can be used to calculate energies (not gradients) using the old cavity algorithm of TURBOMOLE 5.7.
The basic cosmo settings are defined in the $cosmo and the $cosmo_atoms block.
Example with default values:

$cosmo
  epsilon=infinity
  nppa= 1082
  nspa=   92
  disex= 10.0000
  rsolv= 1.30
  routf= 0.85
  cavity closed
  ampran= 0.1D-04
  phsran= 0.0
# the following options are not used by default
  allocate_nps= 140 
  use_old_amat 
  no_oc

epsilon=real

defines a finite permittivity used for scaling the screening charges.

allocate_nps=integer

skips the cosmo segment statistics run and allocates memory for the given number of segments.

no_oc

skips the outlying charge correction.

All other parameters affect the generation of the surface and the construction of the A matrix:

nppa= integer

number of basis grid points per atom
(allowed values: k = 10×3ⁱ×n² + 2 = 12, 32, 42, 92...)

nspa= integer

number of segments per atom
(allowed values: k = 10×3ⁱ×n² + 2 = 12, 32, 42, 92...)

disex= real

distance threshold for A matrix elements (Ångstrom)

rsolv= real

distance to outer solvent sphere for cavity construction (Ångstrom)

routf= real

factor for outer cavity construction in the outlying charge correction

cavity closed

  fill in seams between atoms with points

cavity open

  leave untidy seams between atoms

ampran= real

amplitude of the cavity de-symmetrization

phsran= real

phase of the cavity de-symmetrization

use_old_amat

uses $\bf A$ matrix setup of TURBOMOLE 5.7

If the $cosmo keyword is given without further specifications the default parameter are used (recommended). For the generation of the cavity, cosmo also requires the definition of atomic radii. User defined values can be provided in Ångstrom units in the data group $cosmo_atoms, e.g. for a water molecule:

$cosmo_atoms
# radii in Angstrom units
o  1                                                   \
   radius=  1.7200
h  2-3                                                 \
   radius=  1.3000

If this section is missing in the control file, the default values defined in the radii.cosmo file (located in $TURBODIR/parameter) are used. A user defined value supersedes this defaults. $cosmo and $cosmo_atoms can be set interactively with the cosmo input program Cosmoprep after the usual generation of the TURBOMOLE input.

The cosmo energies and total charges are listed in the result section. E.g.:

  SCREENING CHARGE:
    cosmo      :  -0.003925
    correction :   0.003644
    total      :  -0.000282
  ENERGIES [a.u.]:
    Total energy            =      -76.0296831863
    Total energy + OC corr. =      -76.0297567835
    Dielectric energy       =       -0.0118029468
    Diel. energy + OC corr. =       -0.0118765440
    The following value is included for downward compatibility
    Total energy corrected  =      -76.0297199849

The dielectric energy of the system is already included in the total energy. OC corr denotes the outlying charge correction. The last energy entry gives the total outlying charge corrected energy in the old definition used in TURBOMOLE 5.7 and older versions.