[gmx-users] g_angle - Order of Legendre polynomial for ACF - BUG ?

[XAvier Periole]

Dear Dennis,

I believe your problem is due to the fact that when the  
autocorrelation is
done on a dihedral angle a cos function is used instead of the angle  
itself.
This is good to account for periodicity. This function is not  
implemented
in the -P 1 2 3 ... if I recall correctly.

I think you can get around it by giving the data (dihedral angles  
values)
to g_analyse and ask to do the autocorrelation. Or you can get into
autocorr.c and implement the function you'd need.

On May 5, 2009, at 11:58 PM, Dennis Glass wrote:

>
> Hello,
>
> I am facing a problem with g_angle. I want to analyse some  
> dihedrals. When calculating the autocorrelation function, g_angle  
> crashes if I want to use a Legendre polynomial for the ACF. Can I  
> somehow handle this problem?
>
>
> The command lines are below together with the error message. I am  
> using version 4.0.4 of Gromacs. My indexfile contains 4 atoms.
>
>
> DOES WORK:
> g_angle -f run01-10.trr -oc dicorr -type dihedral -n myindexfile
>
>
> DOES NOT WORK:
> g_angle -f run01-10.trr -oc dicorr -type dihedral -n myindexfile -P  
> 1 [or 2, 3]
> ERROR MESSAGE:
> -------------------------------------------------------
> Program g_angle, VERSION 4.0.4
> Source code file: autocorr.c, line: 607
>
> Fatal error:
> Incompatible options bCos && bVector (autocorr.c, 608)
> -------------------------------------------------------
>
>
> Thanks for your help
> Dennis
>
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