Hi all,<br><br>I am working with GROMOS 53a6 ff in GROMACS 4.5, and I assume a Lennard-Jones interaction function was used for short-range vdw interactions.<br><br>From the reference paper <i>A Biomolecular Force Field Based on the Free Enthalpy of Hydration and Solvation: The GROMOS Force-Field Parameter Sets 53A5 and 53A6</i>, I found that for example,<br>
<br>when rvdw = 1.5nm, the repulsion term of the interaction between two CH1 type atoms (C12ij = 9.85^2) can be calculated as 9.850*9.850 / (1.5^12) = 0.747786 kJ/mol. So I wonder if this value is considered to be small enough to be ignored.<br>
<br>In addition, it seems not until 5 nm does the dispersion term become larger than the repulsion term in this case, so would turning on Dispersion Correction between, say 1.5 to 5 nm introduce more errors than turning it off?<br>
<br>Any suggestion would be appreciated!<br><br>Thanks,<br><br>Yun Shi<br>