[gmx-users] Energy drift

Xiaobin Cao xcao at lsu.edu
Wed Aug 20 15:56:11 CEST 2014


Thanks for your response, Mark. Can you help me to check the parameters for my mdp file to see if it is correct? Can you send me a mdp file for NVE? I will test it today. 

By the way, my GROMACS version is single precision? Does it matter?

>Given that their bond constant for N-N is ~4.5 times higher than their bond
>constant for C-H, and both have comparable equilibrium lengths, and
>unconstrained C-H bonds are normally treated with either 1fs or 0.5fs, and
>that time step should be rather shorter than the period of bond
>oscillation, I'd have serious reservations about the quality of that model,
>and your results suggest reason for that. If you've got the parameters
>right, then you should be able to suppress (post-equilibration) NVE drift
>from integration inaccuracy by taking a time step that is small enough. How
>small is small enough?

>Mark

>Thank you
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