[gmx-users] Gravity in MD-simulations

[Janne Hirvi]

Hello gmx-users!

I would like to inquire if there is some sensible way to take into account
gravity in molecular dynamics simulations. I have understood that it is
possible to introduce constant acceleration on certain group in Gromacs with
options acc_grps and accelerate which the latter should be 0.0 0.0 -9.81E-15
(nm/ps^2) in case of gravity. However if the displacement is proportional to
the second power of time, (x=1/2*a*t^2) simulation of nanosecond should induce
displacement of only 5E-18m, which is neglible. Have I understood this
correctly and/or is there some other way to visualize real gravity effects
within the time-scale of MD-simulations? 

Thanks for any help,

Janne
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Janne Hirvi, MSc(Physical Chemistry), Researcher
University of Joensuu, Department of Chemistry, P.O.Box 111 80101 Joensuu, FI
Tel: +358 13 2514544 & +358 50 3474223
E-mail: Janne.Hirvi at joensuu.fi & hirvi at cc.joensuu.fi
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