CCL:G: H-bond distance with different solvation models

[Ramon Crehuet <rcsqtc/./iqac.csic.es>]

 Sent to CCL by: Ramon Crehuet [rcsqtc_+_iqac.csic.es]
 Dear all,
I would like to study the dependence of an H-bond distance with the
 dielectric
 constant of water (which depends on temperature, pressure, etc). My
 system
 consists of a water molecule and a small molecue containg a donating NH
 group. I
 have run the same calculations with Gaussian, using the PCM model and
 with Orca,
 using the Cosmo model, obtaining different results.
 For an epsilon range of 80-95, the Cosmo in Orca changes the H-bond
 from 1.85A
 to 1.95A. The same model with Gaussian PCM gives a distance that is
 constant to
 3 significant digits: 1.897A.
 Gaussian seems to be correctly reading the epsion, as the log file states:
 Solvent              : Water, Eps=  95.000000 Eps(inf)=   1.777849
Being electrostatic in character, I would expect the H-bond distance
 to depend
 on the dielectric constant. Beyond that, are there any reasons to
 prefer one of
 the methods?
 Thanks in advance,
 Ramon
 --
 Ramon Crehuet
 Cientific Titular (Assistant Professor)
 Institute of Advanced Chemistry of Catalonia
 IQAC - CSIC
 http://www.iqac.csic.es/qteor
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