Re: [gmx-users] Does gmx distance correct for broken molecules from pbc?

2017-08-04 Thread Mark Abraham
Hi,

gmx help distance shows that there are two PBC-related options. Perhaps
your answer lies there.

Mark

On Fri, Aug 4, 2017 at 9:47 AM Ramon Crehuet 
wrote:

> Dear all,
>
> I have a system composed of a trimeric protein and a double stranded DNA.
> I would like to calculate the distance between the center of mass (com) of
> the protein and the com of the DNA (I am working with the NVT equilibration
> trajectory as an example). I tried:
>
>
> gmx distance -f nvt.trr -s nvt.tpr -select 'com of group Protein plus cog
> of group DNA' -xvg none -oall -rmpbc
>
> This gave distances that seem too long. Then I created a trajectory
> removing the PBC:
>
> gmx trjconv -f em.gro -s em.tpr -o whole.pdb -pbc nojump
> gmx trjconv -f nvt.trr -o whole.xtc -s whole.pdb -pbc nojump
>
> And calculated the distances again:
>
> gmx distance -f whole.xtc -s whole.pdb -select 'com of group Protein plus
> cog of group DNA' -xvg none -oall -rmpbc
>
> This gives reasonable results, different from the previous call to gmx
> distance. In an attempt to avoid calculating the whole.xtc trajectory I
> gave a pdb file that doesn't have broken molecules:
>
> gmx distance -f nvt.trr -s whole.pdb -select 'com of group Protein plus
> cog of group DNA' -xvg none -oall -rmpbc
>
> But this still gives the wrong result. I thought the flag -rmpbc would
> make molecules whole, but apparently it doesn't in my case. Is there a way
> to calculate the distance directly from the original trajectory?
>
>
> Thanks in advance,
>
> Ramon
>
>
>
> --
>
>
> Ramon Crehuet
>
> Cientific Titular (Assistant Professor)
>
> Institute of Advanced Chemistry of Catalonia IQAC - CSIC
>
> scholar.google.es/citations?user=PIHmEiwJ
> orcid.org/-0002-6687-382X
> publons.com/a/1018637/
> twitter.com/rcrehuet
> ramoncrehuet.wordpress.com
>
> Tel. +34 934006116 <+34%20934%2000%2061%2016>
> Jordi Girona 18-26
> 08034 Barcelona (Spain)
> --
> Gromacs Users mailing list
>
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[gmx-users] Does gmx distance correct for broken molecules from pbc?

2017-08-04 Thread Ramon Crehuet
Dear all, 

I have a system composed of a trimeric protein and a double stranded DNA. I 
would like to calculate the distance between the center of mass (com) of the 
protein and the com of the DNA (I am working with the NVT equilibration 
trajectory as an example). I tried: 


gmx distance -f nvt.trr -s nvt.tpr -select 'com of group Protein plus cog of 
group DNA' -xvg none -oall -rmpbc 

This gave distances that seem too long. Then I created a trajectory removing 
the PBC: 

gmx trjconv -f em.gro -s em.tpr -o whole.pdb -pbc nojump 
gmx trjconv -f nvt.trr -o whole.xtc -s whole.pdb -pbc nojump 

And calculated the distances again: 

gmx distance -f whole.xtc -s whole.pdb -select 'com of group Protein plus cog 
of group DNA' -xvg none -oall -rmpbc 

This gives reasonable results, different from the previous call to gmx 
distance. In an attempt to avoid calculating the whole.xtc trajectory I gave a 
pdb file that doesn't have broken molecules: 

gmx distance -f nvt.trr -s whole.pdb -select 'com of group Protein plus cog of 
group DNA' -xvg none -oall -rmpbc 

But this still gives the wrong result. I thought the flag -rmpbc would make 
molecules whole, but apparently it doesn't in my case. Is there a way to 
calculate the distance directly from the original trajectory? 


Thanks in advance, 

Ramon 



-- 


Ramon Crehuet 

Cientific Titular (Assistant Professor) 

Institute of Advanced Chemistry of Catalonia IQAC - CSIC 

scholar.google.es/citations?user=PIHmEiwJ 
orcid.org/-0002-6687-382X 
publons.com/a/1018637/ 
twitter.com/rcrehuet 
ramoncrehuet.wordpress.com 

Tel. +34 934006116 
Jordi Girona 18-26 
08034 Barcelona (Spain)
-- 
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