Hi,

I'm using sorption (MS 5.5) to calculate the Henry constant of different ions in nanotubes. I satrted by conducting a size test to determine the optimum length of the nanotube to be used and found out that both the isosteric heat and henry constant vary with tube length. (for the latter, that is after normalising with tube lenght; as the Henry constat calculated by the program is the load per cell/kPa)

A periodic structure is built, 10,10 single wall Nanotube (using the "Build nanostructure" utility), I then asign a charge of +0.04 to each carbon atom. With this unit cell I then build 3 nanotube with different number of repeated units: 8, 16, and 32.

When I run a Henry calculation with these 3 nanotubes and F- as the sorbate, using ultrafine energy settings, ewald precision of 1e-5, and the universal forcefield, and constraining the insertion to the centermost part of the box, the values of the isosteric heat reported for the three simulations differ.

The difference appears to be caused by the addition/substraction of a constant (maybe long tail corrections) as the energy profile has exactly the same shape for the three cases (but shifted several kCal, as shown in the attached figure)

Has anyone encountered/found a similar problem?

Julio