FAQ
***


I want to include solvent effects, do I need COSMO-RS?
======================================================

You do not need COSMO-RS to do ADF calculations with continuum
solvation (see COSMO vs COSMO-RS FAQ). If you want to calculate
thermodynamic properties like partition coefficients, VLE,
solubilities, etc. you do need COSMO-RS. COSMO-RS usually also yields
more accurate solvation free energies and pKa values than COSMO.


Do I need to use the ADF module with COSMO-RS?
==============================================

Many researchers and engineers use ADF together with COSMO-RS. If you
want to add new compounds that are not yet available in our database,
the recommended approach is to use the **COSMO-RS Compound task**,
because COSMO-RS is sensitive to the sigma profile and its parameters
are calibrated for profiles generated in this way.

For simpler cases, **FastSigma** can estimate the sigma profile
directly from the SMILES representation of your compound. However, it
may not support compounds containing uncommon elements or functional
groups, and it does not support ionic compounds.

If **FastSigma** is not suitable for your compound, you may consider
the **MOPAC** in our DFTB module, which is faster than ADF.

In practice, the expected accuracy is generally in the following
order: **COSMO-RS Compound task** > **FastSigma** > **MOPAC**. For
more details, please see COSMO result files.

In particular:
   * Steps 1–3 describe the COSMO-RS Compound task

   * Step 6 describes the MOPAC approach

   * Step 7 describes FastSigma


Can I use a .cosmo file from COSMOlogic, Dmol3, or Gaussian with ADF COSMO-RS?
==============================================================================

In principle, yes, but your are advised to rerun the COSMO calculation
with ADF rather than using sigma profiles from Turbomole, Gaussian,
DMol3 or another code. Since ADF uses a slightly different procedure
(gas phase optimization followed by COSMO calculation with an infinite
dielectric constant) as well as different technical settings (scalar
relativistic, triple-zeta Slater-type basis set, integration, surface
charge generation with a finer grid), our COSMO-RS implementation has
been reparametrized specifically for use with sigma profiles generated
in that way. Therefore, you are advised to follow the set procedure in
ADF, easiest is to use the COSMO-RS preset in the ADF GUI. See for
details: C.C. Pye, T. Ziegler, E. van Lenthe, J.N. Louwen, An
implementation of the conductor-like screening model of solvation
within the Amsterdam density functional package. Part II. COSMO for
real solvents, Can. J. Chem.87, 790 (2009). If you do insist on using
sigma profiles generated with the other programs with different
defaults, you can use the cosmo2kf utility to convert the plain ascii
cosmo files to our binary file format. There are also scripting tools
for COSMO-RS to facilitate screening solvent (combinations) for
activities, partition coefficients, VLE, etc.


For which compounds do you have sigma profiles in the database?
===============================================================

We have text files for the regular compounds and ionic liquids. If you
install the databases you can also search on elemental composition.


I have COSMO-RS download permissions but I can not automatically download the COSMO-RS databases?
=================================================================================================

Some firewalls prevent the automatic download of the COSMO-RS
database. With your SCM User ID and password you can download the
compounds database manually (see also video on how to install it on
Windows for AMS2021).
