[Pw_forum] ENVIRON vs COSMO solvation models

[Giuseppe Mattioli]

Dear Oliviero
Thank you for your prompt and detailed answer!
I will surely contact you in private for further discussions.
Best Wishes
Giuseppe

On Wednesday, March 09, 2016 10:49:52 AM Oliviero Andreussi wrote:
> Hi Giuseppe,
> 
> You can play with the same two parameters in Environ as well, you just
> need to set env_static_permittivity (and env_optical_permittivity for
> TDDFT) to the ones of the medium you want to simulate. This is assuming
> that you are only interested in the electrostatic interaction with the
> solvent and that the shape of the cavity, i.e. how close to the solute
> you get the continuum solvent, does not depend on the kind of solvent.
> Both these assumptions are implicit in your analogy with COSMO (which by
> the way is a less refined continuum model than the standard PCM or than
> the SCCS model of Environ), but they may be crude depending in the
> system/property you want to study. In particular, I am quite sure that
> standard PCM uses a different scaling of the size of the cavity for
> different solvents.
> 
> Clearly, if you are only interested in studying the effects of a
> different dielectric constant of the environment on your embedded
> quantum-mechanical system (e.g. as was done in Fortunelli et al. Angew.
> Chem. Int. Ed. 126, 6787 (2014) doi:10.1002/ange.201403264) you can do
> it very easily with the parameters above. Instead of using one of the
> preset solvent setups (environ_type =
> vacuum/water/water-cation/water-anion), you specify in input only the
> dielectric constant that you want to use, env_static_permittivity = XXX,
> and use the defaults for all the other parameters (which corresponds to
> no contribution from non-electrostatic terms, env_pressure = 0.D0,
> env_surface_tension = 0.D0, and to a shape of the cavity equal to the
> one optimized for water, rhomax = 0.005, rhomin = 0.0001).
> 
> Otherwise, if you have to study a well defined solvent and want to be
> more accurate, you would need to redo the parametrization of the model
> for the new solvent, which for Environ only requires to tune 3 (or 4)
> parameters (rhomax and rhomin, which controls the shape of the cavity,
> env_static_permittivity and env_pressure, which are used to model non
> electrostatic effects in a simplified way). Ideally you want to tune
> these parameters to reproduce experimental solvation free energies of a
> reasonable range of solutes in the new solvent (a good database of
> experimental data is from the group of Truhlar
> http://comp.chem.umn.edu/mnsol/ ).
> 
> Since I am trying to improve on the documentation of the module, which
> probably is not clear enough, can I ask you which documentation have you
> been studying? The website (www.quantum-environ.org), the input keywords
> (as in the Environ/Doc/ directory or from the website
> http://nebula.wsimg.com/c3d04ee804fb1a1ddb5402d80b7c8194?AccessKeyId=ECF106C2B7F0B5C40F7B&disposition=0&alloworigin=1
> ), the references? If you have more doubts on setting up the input or on
> the implemented models, please don't hesitate to write to the forum or
> to contact me directly.
> 
> Regards,
> 
> Oliviero Andreussi
> 
> > Dear All
> > I was studying the documentation of the ENVIRON 0.2 plugin and it seems that water only is coded as solvent for isolated molecules. I was
> > wondering
> > whether there is somewhere a subset of variables (which I was not able to found...) that setup alternative dielectric media as in the case of the
> > COSMO model (cited in the ENVIRON documentation), which basically requires the solvent dielectric constant (ground state DFT) or dielectric
> > constant+refractive index (TDDFT) only.
> > Thank you in advance
> > Giuseppe
> > 
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> >     Giuseppe Mattioli
> >     CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
> >     v. Salaria Km 29,300 - C.P. 10
> >     I 00015 - Monterotondo Stazione (RM), Italy
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********************************************************
- Article premier - Les hommes naissent et demeurent
libres et égaux en droits. Les distinctions sociales
ne peuvent être fondées que sur l'utilité commune
- Article 2 - Le but de toute association politique
est la conservation des droits naturels et 
imprescriptibles de l'homme. Ces droits sont la liberté,
la propriété, la sûreté et la résistance à l'oppression.
********************************************************

   Giuseppe Mattioli                            
   CNR - ISTITUTO DI STRUTTURA DELLA MATERIA   
   v. Salaria Km 29,300 - C.P. 10                
   I 00015 - Monterotondo Stazione (RM), Italy    
   Tel + 39 06 90672836 - Fax +39 06 90672316    
   E-mail: <giuseppe.mattioli at ism.cnr.it>
   http://www.ism.cnr.it/english/staff/mattiolig
   ResearcherID: F-6308-2012