[gmx-users] Re: viscosity and acflen in g_energy

Mark Abraham Mark.Abraham at anu.edu.au
Sun Sep 27 23:57:25 CEST 2009

Vitaly V. Chaban wrote:
> Mark,
> In "g_energy -h" I see nothing abous viscosity except the option
> "-vis". The command line is as I  wrote earlier:
> "g_energy -vis -acflen 1001"
> The system is liquid water. The simulation time is 2 000 ps. The file
> I look into is enecorr.xvg.
> What the error of some sort do you mean?

-acflen is measured in trajectory frames. How many relevant frames exist 
in the trajectory file?


> Vitaly
>>> When using g_energy to calculate viscosity ("g_energy -vis"), in
>>> enecorr.xvg the ACF of stress tensor is output. How can one specify
>>> the "acflen" of this ACF?
>>> I try the key "g_energy -vis -acflen XXX" but the length of the ACF is
>>> still equal to the half of the trajectory length.
>> If you read g_energy -h, you will need to specify the ACF length in a
>> particular way. If you'd given us your actual command line and some
>> information about your trajectory, you might have gotten a definitive
>> answer... as it is, we can only assume you made an error of some sort! :-)

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