CCL: Adding many explicit water molecules to the model

[Christoph Riplinger <riplinger()faccts.de>]

 Sent to CCL by: Christoph Riplinger [riplinger]*[faccts.de]
 Dear Grigoriy,
a recent example can be found here:
 https://pubs.acs.org/doi/pdf/10.1021/acs.jctc.1c00582
There you find a comparison of different approaches to compute EPR
 properties of a pH-sensitive spin probe, including explicit solvent
 (which was crucial): using snapshots from an MD, QM/MM, CCSD, EC-RISM,
 and CPCM.
 Best,
 Christoph
 On 12/19/22 10:15, Grigoriy Zhurko reg_zhurko_-_chemcraftprog.com wrote:
>  I need to compute the pKa values of some carbon acids and phenols, and it is a
>  common practice to add 1-3 explicit water molecules, bonded with polar groups of
>  the studied molecule, to better take into account the specific solvation effects
>  (in addition to CPCM model). I tried to add many water molecules (14) for better
>  results – see attached picture. The results are interesting. At one side,
>  possibly very big error is produced by the existence of many local minimums with
>  different numbers of h bonds. How these minimums should be named in paper
>  – maybe “conformations”, “configurations”,
>  “geometrical configurations”, “local minimums”?
>  Then I found, that if the computation of different acids is performed with same
>  geometrical configurations of 5 h2o molecules bound to –COOH, and with
>  same configurations for neutral molecule and anion, possibly the results are
>  quite good (a common correlation can be obtained for carbon acids and phenols).
>  So I want to publish these results; but I need to read more works when this
>  approach (adding many explicit water molecules) was used. Can you suggest such
>  papers?
>  By the way, using my program Chemcraft is important for such jobs, because the
>  “Structures merger” utility in in allows one to transfer several
>  H2O molecules in same configuration from one acid to another.
>  Grigoriy Zhurko
>  https://chemcraftprog.com
 --
 FAccTs GmbH
 Rolandstrasse 67, 50677 Köln
 Amtsgericht Köln HRB 88406
 Geschäftsführer: Dr. Christoph Riplinger
 https://www.faccts.de | https://twitter.com/faccts_orca