[gmx-users] Re: relative weight between the direct space sum and reciprocal space sum

[Janne Hirvi]

Hello!

Yes, I think you cant set the beta parameter directly but you can calculate it
from the equation 

erfc(beta*r)/r = ewald_rtol 

at the cut-off (=rcoulomb) and so set the ewald_rtol parameter to match to the
wanted beta parameter.

Janne


> HI, 
> 
> according to the 3.2 gromacs manual , the ewald_rtol parameter is the
> relative strength of the electrostatic interaction at the cut off, decreasing
> this gives a more accurate direct sum, but a less accurate reciprocal sum(p.
> 81).
> The beta parameter is the parameter that determines the relative weight
> between the direct sum and reciprocal sum(p.55) but i don't think you can set
> the beta parameter in gromacs