[gmx-users] About EWD3DC in Gromacs 3.3 Beta (9.9.2005)

[Janne Hirvi]

Hello!

I installed Gromacs version dated on 9.9.2005 and looked at code ewald_util.c,
which was corrected by Berk Hess from the version 3.2. I am not programmer so I
don't quite get the meaning of fr->epsilon_r, but even I think how hard I
can't
fit these equations of dipole_coeff to those in article of Yeh and Berkowitz.

For case EWD3D:

Code:
dipole_coeff = 2*M_PI*ONE_4PI_EPS0/((2*epsilon_surface + fr->epsilon_r)*vol);

Article:
dipole_coeff = 2*M_PI*ONE_4PI_EPS0/((2*epsilon_surface + 1)*vol);

and

for case EWD3DC:

Code:
dipole_coeff = 2*M_PI*(ONE_4PI_EPS0/fr->epsilon_r)/vol;

Article:
dipole_coeff = 2*M_PI*ONE_4PI_EPS0/vol;

I can't get original publication of Smith, so the last one might be for vacuum
case or should it really be independent from permittivity. However equations
from the article of Yeh and Berkowitz equal to the code of version 3.2, which
had some other errors (if I understood right). 


Thanks for any comments! 

Janne

-----------------------------------------------------------------------------
Janne Hirvi, MSc(Physical Chemistry), Researcher
University of Joensuu, Department of Chemistry, P.O.Box 111 80101 Joensuu, FI
Tel: +358 13 2513326 & +358 50 3474223
E-mail: Janne.Hirvi at joensuu.fi & hirvi at cc.joensuu.fi
-----------------------------------------------------------------------------