# 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 surface; 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
```