Example: COSMO: HCl¶

#! /bin/sh


# Computing solvent effects, with the COSMO model, is illustrated in the HCl
# example.

# After a non-solvent (reference) calculation, which is omitted here, two
# solvent runs are presented, with somewhat different settings for a few input
# parameters. The block key Solvation controls all solvent-related input.

# All subkeys in the SOLVATION block are discussed in the User's Guide. Most of
# them are rather technical and should not severely affect the outcome.
# Physically relevant is the specification of the solute properties, by the
# SOLVENT subkey: the dielectric constant and the effective radius of the
# solvent molecule.

# Note that a non-electrostatic terms as a function of surface area is included
# in the COSMO calculation, by setting the values for CAV0 and CAV1 in the
# subkey SOLVENT of the key SOLVATION. In ADF2010 one should explicitly include
# such values for CAV0 and CAV1, otherwise this non-electrostatic term will be
# taken to be zero, since the defaults have changed in ADF2010.

# A rather strong impact on the computation times has the method of treating the
# 'C-matrix'. There are 3 options (see the User's Guide): EXACT is the most
# expensive, but presumably most accurate. POTENTIAL is the cheapest alternative
# and is usually quite adequate. EXACT uses the exact charge density for the
# Coulomb interaction between the molecular charge distribution and the point
# charges (on the Van der Waals type molecular surface) which model the effects
# of the solvent. The alternatives, notably 'POTENTIAL', use the fitted charge
# density instead. Assuming that the fit is a fairly accurate approximation to
# the exact charge density, the difference in outcome should be marginal.


AMS_JOBNAME=Gas $AMSBIN/ams <<eor
System
  symmetrize
  atoms
     H    0.000000     0.000000    0.000000
     Cl   1.304188     0.000000    0.000000
  end
end

Task SinglePoint

Engine ADF
  title HCl(0) reference run (gas phase)
  eprint
    scf NoEigvec
  end
  basis
    type DZP
    CreateOutput Yes
  end
  noprint Bas EigSFO EKin SFO, frag, functions
EndEngine
eor



AMS_JOBNAME=Exact $AMSBIN/ams <<eor
System
  atoms
     H    0.000000     0.000000    0.000000    adf.R=1.18
     Cl   1.304188     0.000000    0.000000    adf.R=1.75
  end
end

Task SinglePoint

Engine ADF
  title HCl(1) Solv-excl surfac; Gauss-Seidel (old std options)
  eprint
    scf NoEigvec
  end
  noprint Bas EigSFO EKin SFO, frag, functions
  basis
    type DZP
  end
  solvation
    c-mat Exact
    charged Method=Gauss-Seidel
    disc SCale=0.01  LEGendre=10 TOLerance=1.0e-2
    div ND=4  min=0.5  Ofac=0.8
    scf Variational
    solv epsilon=78.8 radius=1.4 cav0=1.321 cav1=0.0067639
    surf delley
  end
  symmetry NOSYM
EndEngine
eor


# In the second solvent run, another (technical) method is used for determining
# the charge distribution on the cavity surface (conjugate-gradient versus
# Gauss-Seidel in the previous calculation), and the POTENTIAL variety is used
# for the C-matrix handling. The results show that it makes little difference in
# outcome, but quite a bit in computation times.

AMS_JOBNAME=Potential $AMSBIN/ams <<eor
System
  symmetrize
  atoms
     H    0.000000     0.000000    0.000000    adf.R=1.18
     Cl   1.304188     0.000000    0.000000    adf.R=1.75
  end
end

Task SinglePoint

Engine ADF
  title HCl(9) NoDisk and Cmatrix potential
  eprint
    scf NoEigvec
  end
  noprint Bas EigSFO EKin SFO, frag, functions
  basis
    type DZP
  end
  solvation
    c-mat POTENTIAL
    charged Method=conjugate-gradient
    div ND=4  min=0.5  Ofac=0.8
    scf Variational
    solv epsilon=78.8 radius=1.4 cav0=1.321 cav1=0.0067639
    surf delley
  end
EndEngine
eor