# [gmx-users] Re: what is sigma in gromacs? the radius of a sphere or the diameter of a sphere?

grita cemilyigit at arcor.de
Thu Aug 15 14:42:07 CEST 2013

Hi Justin,

What I want to understand is the following:

I have two particles and the interaction diameter should be 5 angstroms.

The \sigma in this formulas

c^6 = 4 \epsilon \sigma^6
c^12 = 4 \epsilon \sigma^12

would be 5, or?

Best, grita

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