Home > Community > How is it possible to calculate a distance between a water...
Upvote

28

Downvote
+ Mass
+ Molecular dynamics
+ Atoms
+ Molecular structure
+ Water
+ Pdb
Posted by
Leobert Samarita

How is it possible to calculate a distance between a water...

David Sandiford  Follow

Hey Stefania, 
I would write a simple tcl script that can be launched in VMD http://www.ks.uiuc.edu/Research/vmd/ (or with VMD by giving the -dispdev text command) while you load a PDB file. If I correctly understand your problem, I would load the file select the water molecule(s) of interest and then measure the distance of those atoms (you can easily pick the atoms that are within a cutoff from any selection (in your case a water molecule) http://www.ks.uiuc.edu/Research/vmd/vmd-1.7.1/ug/node17.html). You can iterate through the collected frames of the trajectory and then write this distance in a text file that you can plot using a plotting software (command to measure distance using vmd: http://www.ks.uiuc.edu/Research/vmd/vmd-1.9/ug/node135.html). Once you have the script you should be able to launch it while you load your coordinates and trajectory using VMD. Something like this: vmd COORDINATE TRAJECTORY -dispdev text < YOURSCRIPT.tcl Hope this helps, Cheers, Davide.

More

Upvote

VOTE

Downvote
Asad Hussain  Follow

Hey Stefania, 
I would write a simple tcl script that can be launched in VMD http://www.ks.uiuc.edu/Research/vmd/ (or with VMD by giving the -dispdev text command) while you load a PDB file. If I correctly understand your problem, I would load the file select the water molecule(s) of interest and then measure the distance of those atoms (you can easily pick the atoms that are within a cutoff from any selection (in your case a water molecule) http://www.ks.uiuc.edu/Research/vmd/vmd-1.7.1/ug/node17.html). You can iterate through the collected frames of the trajectory and then write this distance in a text file that you can plot using a plotting software (command to measure distance using vmd: http://www.ks.uiuc.edu/Research/vmd/vmd-1.9/ug/node135.html). Once you have the script you should be able to launch it while you load your coordinates and trajectory using VMD. Something like this: vmd COORDINATE TRAJECTORY -dispdev text < YOURSCRIPT.tcl Hope this helps, Cheers, Davide.

More

Upvote

VOTE

Downvote
Benson Wangombe  Follow

To add to Davide's answer: I would recommend using the collective variables plugin of VMD. The "distance" collective variable will measure the COM distance between two groups; you can define the water molecule as one and the other atoms of interest as the other group. The advantage of this method is that you can indicate whether you want the absolute distance or the shortest distance (if periodic boundaries were used). General information for running the VMD colvars module can be found here: http://www.ks.uiuc.edu/Research/vmd/current/ug/node211.html and more info on the distance colvar can be found here: http://www.ks.uiuc.edu/Research/vmd/current/ug/node227.html#SECTION001641100000000000000

More

Upvote

VOTE

Downvote
Chang Liu  Follow

Use VMD for such calculation, you can use following script

More

Upvote

VOTE

Downvote
Amos Patrick  Follow
Upvote

VOTE

Downvote