[gmx-users] using g_angle

Mark Abraham Mark.Abraham at anu.edu.au
Wed Feb 29 16:00:55 CET 2012


On 1/03/2012 1:00 AM, francesca vitalini wrote:
> Hi Mark,
> Thanks for your answer. What I'm trying to do is calculate the value
> in degrees of  the angles listed in my index file. If my index file
> looks like
> [ dihedral 1 ]
> 2  7  9  10
> [ dihedral 2 ]
> 10  16  18  19

I said in my last email that my suggestion of a separate group group for 
each angle was wrong and that your original index file like

[ dihedrals ]
2 5 9 10
10 15 18 19
.....

was fine. Please try that with g_angle -ov -all. I get output like

# This file was created Mon Feb 20 12:32:15 2012
# by the following command:
# g_angle -f 005_5 -type dihedral -all -ov 005_5_angles.xvg -n 
../1oei_sim_backbone_angle.ndx
#
# g_angle is part of G R O M A C S:
#
# GRoups of Organic Molecules in ACtion for Science
#
@    title "Average Angle: Backbone_dihedral_angles"
@    xaxis  label "Time (ps)"
@    yaxis  label "Angle (degrees)"
@TYPE xy
245757.00000    19.937     1.923   -61.394   -74.236    27.453    
-2.719  -179.194    96.730   -27.468    43.121    -8.608    -0.480    
-0.764     0.001  -179.750   170.982   157.245  -174.933    37.563    
40.854    93.329    19.823   169.543   129.371    40.443  -149.558     
8.198    43.427   100.089    86.565   154.344   171.804    52.401  
-158.571    27.166  -143.253    39.944     6.985   178.488   179.865    
-0.432   179.965  -179.957   179.499  -179.774  -179.788   107.176   
151.312   -37.770
245762.00000    22.309    -1.821   -60.416   -73.830   -21.904    
-2.231  -179.111    96.693  -114.414    40.600  -154.543     0.922    
-2.143     0.932   179.704   -71.467   147.204   171.571    52.328    
39.069    70.499     3.113   179.355    91.086    43.155   133.656   
-22.505    23.643   104.997   105.160   151.335  -176.456   176.378    
23.691     6.447  -102.512    43.837    33.328  -179.572  -179.286     
1.288   179.801   179.207  -179.029  -178.575   179.950   151.692   
164.967    -4.967
245763.00000    36.760    -1.567   -59.734   -74.259   -88.956     
9.191   175.880    91.328  -106.962    38.466  -159.767    -0.092     
1.363    -0.665  -179.743   -63.435   159.398   168.167    42.926    
40.201    86.058    15.792   171.260   108.564    37.481   148.734   
-19.163    41.603    95.716   100.927   159.081   177.076   170.625    
18.814    11.879  -108.608    42.251    31.301  -179.193  -179.047     
0.401  -179.484   179.431   179.957   179.578   179.770   143.532   
159.744    -1.341


Mark

> then if I use the command line
>
> g_angle -f aa.gro -s aa.tpr -n angles_prova.ndx -ov angav_prova3.xvg
> -all -type dihedral
> or the same with the flag -od,
> what I get is an interactive menu where I have to choose the group and
> if I choose one then I obtain an output file which looks like
> # This file was created Wed Feb 29 14:54:55 2012
> # by the following command:
> # /home/cocktail/vitalini/gromacs_special/bin/g_angle -f aa.gro -s
> aa.tpr -n angles_prova.ndx -od angav_prova3.xvg -all -type dihedral
> #
> # /home/cocktail/vitalini/gromacs_special/bin/g_angle is part of G R O M A C S:
> #
> # Great Red Oystrich Makes All Chemists Sane
> #
> @    title "Dihedral Distribution: dihedral"
> @    xaxis  label "Degrees"
> @    yaxis  label ""
> @TYPE xy
> @    subtitle "average angle: -6192.3\So\N"
>        -109    0.000000
>        -108    1.000000
>        -107    0.000000
>
> Which does what I'm looking for but this means that I'll need a file
> for each angle. Is there a faster way to get a file that has like two
> columns, one for the dihedral and another one for the angles?
> Thanks
> Francesca
>
> 2012/2/29 Mark Abraham<Mark.Abraham at anu.edu.au>:
>> On 29/02/2012 11:54 PM, francesca vitalini wrote:
>>> 2012/2/29 Mark Abraham<Mark.Abraham at anu.edu.au>:
>>>> On 29/02/2012 9:39 PM, francesca vitalini wrote:
>>>>> Hi all,
>>>>> I'm trying to use g_angle to calculate a list of dihedrals that I have
>>>>> into an hand made index file (angles.ndx), which looks like
>>>>> [ dihedrals ]
>>>>> 2 5 9 10
>>>>> 10 15 18 19
>>>>> .....
>>>>
>>>> mk_angndx might have helped.
>>> Actually mk_angndx gies me the angles for phi and psi while instead I
>>> need omega and they are put in  a strange format like in groups of 8
>>> instead of 4.
>>
>> Whitespace inside the index group probably doesn't matter.
>>
>>
>>>>> However it produces a .xvg file where it gives me for each angle in
>>>>> degrees its probability. However, what I want is instead to know the
>>>>> value in degrees of each angle in the ndx file. Do you have any
>>>>> suggestions apart from building an index file for each angle?
>>>>
>>>> g_angle -ov -all with each angle in its own group.
>>> What do you mean with each angle in its own group? something like
>>> [dihedrals]
>>> 2 5 9 10
>>> [dihedrals]
>>> 10 13 16 18
>>> ...
>>
>> Yes, but with unique group names - but it turns out I was wrong to suggest
>> that. Your index file above is fine.
>>
>>
>>> Isn't it equivalent to build differend index files?
>>> anyway the -ov flag gives the average over time, but I need the angles
>>> just at one time, that is why I was using -od but it just plots the
>>> distribution of all angles together.
>>> Any help?
>>
>> Which part of the output of g_angle -ov **-all** doesn't suit you?
>>
>> Mark
>>
>>
>>> Thanks
>>>
>>>> Mark
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