[gmx-users] Shift Electrostatic Summation

[Mark Abraham]

Shuangxing Dai wrote:
> Thank you for your help. Yes, when I found the user define part for 
> electrostatics, I hope I can use this part since the analytic form of my 
> potential is known. However, since there is a self energy term exist and 
> then the whole energy cannot be decomposed to pair interactions because 
> I cannot specify how much to each pair since the number of neighbours is 
> unkown. That is why I am confused. So I still need an new electrostatic 
> summation similiar to shift, not just a new pair interaction.

The number of neighbours is known at run-time. However, I still don't 
see why this matters - see 
http://www.gromacs.org/pipermail/gmx-users/2009-March/040830.html

> And I cannot understand/find how the force for Shift electrostatic 
> summation is calculated in force.c since there is no formula for force 
> found. Or I find the wrong place? And if I want to modify the force 
> formula for Shift, where is it?

Look in the nonbonded kernels - like I said in the above post and 
previously.

Mark