[gmx-users] Re:polymer chain length and density

Dr. Vitaly V. Chaban vvchaban at gmail.com
Thu Oct 27 02:37:15 CEST 2011

> Dear experts,
> I have a quick and naive inquiry. I see in the molecular dynamics
> simulations that density of the polymers increase slightly with increasing
> degree of polymerization ( or Mw). Even for the systems having the same
> total atom numbers but one with less number of chains of higher Mw. My guess
> its because of the less void space in case of higher Mw chains..?!

It is because the interatomic distances between chemically bonded
atoms are noticeably smaller than between the atoms of just
neighboring molecules.

I think when you come to publishing your results, you will need to
exactly specify the number of monomers in your chain. It may also be
interesting to discuss how much your properties are affected by this

> And usually properties depending on Mw level off with no significant change
> in the property of interest vs chain length.

Dr. Vitaly V. Chaban, 430 Hutchison Hall, Chem. Dept.
Univ. Rochester, Rochester, New York 14627-0216

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