Re: Algorithm used by NAMD

From: David Hardy (dhardy_at_ks.uiuc.edu)
Date: Fri Apr 03 2015 - 11:18:46 CDT

Dear Gurpreet Dhindsa,

NAMD integration is effectively the velocity Verlet formulation.

I don't understand what you mean by "also coupled with leap frog."

Best regards,
Dave

--
David J. Hardy, Ph.D.
Theoretical and Computational Biophysics
Beckman Institute, University of Illinois
dhardy_at_ks.uiuc.edu
http://www.ks.uiuc.edu/~dhardy/
On Apr 2, 2015, at 9:55 AM, Gurpreet Kaur Dhindsa <el2275_at_wayne.edu> wrote:
> Dear all.
> I was wondering that NAMD is using only verelt algorithm or it is also coupled with leap frog.
> Can anyone tellme that exact which algorithm is used by NAMD software?
> 
> Thanks,
> Gurpreet Dhindsa
> 
> 
> From: "Aron Broom" <broomsday_at_gmail.com>
> To: "Gurpreet Kaur Dhindsa" <el2275_at_wayne.edu>Cc: "Namd Mailing List" <namd-l_at_ks.uiuc.edu>, owner-namd-l_at_ks.uiuc.edu
> Sent: Tuesday, June 17, 2014 10:58:22 AM
> Subject: Re: namd-l: Merging the two files......
> 
> >Hi Aron,
> >It doesn't show me any problem till equilibration. The problem begins when I am using nMoldyn software to 
> >analyze my data that time time software shows error. Because of that I couldn't analyze it.
> 
> You might need to check with the nMoldyn people then and see what convention they use for systems with more than 99,999 atoms.  You may then need to do some manipulation on the final output before being able to analyze it.
> 
> 
> On Tue, Jun 17, 2014 at 11:44 AM, Aron Broom <broomsday_at_gmail.com> wrote:
> and why do you say this is wrong, have you been unable to use it for your next steps?  
> 
> The PDB format was made with apparently very little (if any) thought towards flexibility.  As a result, it has a fixed number of columns for each piece of information, rather than a special separating character.  Since 5 columns are given to the atom number you can't go past 99999.  So the solution to this is to start using alphabetic characters.  I think you'll find that this works fine for your purposes, and only very old programs might have a problem reading those in.
> 
> Another problem with these fixed columns is that residue and atom names can only be so many characters, leading to very obfuscated names in many cases, and a lot of unintentional overlap when mixing forcefields.  
> 
> 
> On Tue, Jun 17, 2014 at 11:00 AM, Gurpreet Kaur Dhindsa <el2275_at_wayne.edu>wrote:
> Dear all,
> I am trying to merge two different files, one contains 92000 atoms and the other one has
> 40000 atoms. I am using these commands in VMD
> ::TopoTools::mergemols [list 1 2]
> 
> 1,2 are the number of my pdb files in VMD main window.
> At the end, I have total of 130000 atoms. VMD gives me the correct atom number till 99000
> but after that it starts giving me some type of alphabets.
> 
> ATOM  99998  H1  TIP3W5762    -120.414  60.831  -4.134  0.00  0.00      WT1  H
> ATOM  99999  H2  TIP3W5762    -121.121  60.076  -5.310  0.00  0.00      WT1  H
> ATOM  186a0  OH2 TIP3W5764    -116.219  60.562 -10.104  0.00  0.00      WT1  O
> ATOM  186a1  H1  TIP3W5764    -116.062  60.855 -11.001  0.00  0.00      WT1  H
> ATOM  186a2  H2  TIP3W5764    -115.555  61.039  -9.593  0.00  0.00      WT1  H
> ATOM  186a3  OH2 TIP3W5765    -122.951  57.343  13.115  0.00  0.00      WT1  O
> ATOM  186a4  H1  TIP3W5765    -122.161  57.022  13.633  0.00  0.00      WT1  H
> 
> Can someone try merging the files with that number of atoms? Please give me your suggestions.
> 
> Thanks,
> Gurpreet Dhindsa.
> 
> 
> 
> 
> 
> -- 
> Aron Broom M.Sc
> PhD Student
> Department of Chemistry
> University of Waterloo
> 
> 
> 
> -- 
> Aron Broom M.Sc
> PhD Student
> Department of Chemistry
> University of Waterloo
> 
> 

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