[gmx-users] Re[2]: g_msd vs g_velacc

[Vitaly Chaban]

>>For methanol (200ps, dt=0.001):
>> frequency to write velocities = 5
>> frequency to write coordinates = 100
XP> Any rationale behind this difference? That might well result in differences
XP> of C(t) at short times.

Yes, the difference is dictated by the pure logic.

>> $ g_msd
>> 2.3 (and it is true)
XP> How much of msd(t) did you use? The part of the curve you use to fit
XP> to Einstein equation will affect enormously the result!

200 ps of trajectory was used. It is quite enough.

XP> Here you use 1001 points to integrate! Which result to 1001*0.005fs=5 ps!
XP> Again did you use the same length of the msd(t) to fit via Einstein equation?

Sorry, there is no sense in what you say here.