Re: [gmx-users] protein falls apart in energy minimization

2009-05-12 Thread Justin A. Lemkul



Zhong Zheng wrote:
Thanks. That solves the problem. But I still see this warning message: 


Steepest Descents did not converge to Fmax  10 in 201 steps.
Potential Energy  = -1.2866480e+05
Maximum force =  3.4851584e+03 on atom 3683
Norm of force =  6.3128883e+01

That means I should run longer energy minimization until it converges 
well and I don't see this error message. Is that right?


Maybe.  Are you still specifying nsteps = 2000 as in your original message?  If 
so, your machine has converged after 201 steps and you cannot necessarily force 
it to go longer.  You can change emtol and emstep, but you may or may not get a 
substantially different result in the end.  Also realize that Fmax  10 is not 
often achieved in protein systems; Fmax  1000 or  100 is more common.


What you need to be looking at is what is causing the large force.  Look at the 
structure.  What is atom 3683?  Is it positioned too close to something else? 
Is there a geometric problem?


For the purposes of the archive, using -d should only be effective in resolving 
this issue if the box was set up improperly, leading to spurious forces between 
periodic images, if I understand the use of this fix correctly.  Was this the 
case in your system?


-Justin


Thanks.

Zhong

On May 12, 2009, at 12:46 AM, Pawan Kumar wrote:


hi,

Defining a specific box size with -d option in editconf will help to 
overcome this problem...


Regards,
Pawan

On Tue, May 12, 2009 at 8:05 AM, Zhong Zheng zhozh...@gmail.com 
mailto:zhozh...@gmail.com wrote:


hi all

I am running Gromacs on a protein consisted of three chains. But
no matter how I tried, the protein always falls into three parts
(corresponding to each chain) after a simple 2000 steps energy
minimization. Can anyone help me please? Thanks.

Zhong Zheng
___
gmx-users mailing listgmx-users@gromacs.org
mailto:gmx-users@gromacs.org
http://www.gromacs.org/mailman/listinfo/gmx-users
Please search the archive at http://www.gromacs.org/search before
posting!
Please don't post (un)subscribe requests to the list. Use thewww
interface or send it to gmx-users-requ...@gromacs.org
mailto:gmx-users-requ...@gromacs.org.
Can't post? Read http://www.gromacs.org/mailing_lists/users.php


___
gmx-users mailing listgmx-users@gromacs.org 
mailto:gmx-users@gromacs.org

http://www.gromacs.org/mailman/listinfo/gmx-users
Please search the archive at http://www.gromacs.org/search before posting!
Please don't post (un)subscribe requests to the list. Use the
www interface or send it to gmx-users-requ...@gromacs.org.
Can't post? Read http://www.gromacs.org/mailing_lists/users.php





___
gmx-users mailing listgmx-users@gromacs.org
http://www.gromacs.org/mailman/listinfo/gmx-users
Please search the archive at http://www.gromacs.org/search before posting!
Please don't post (un)subscribe requests to the list. Use the 
www interface or send it to gmx-users-requ...@gromacs.org.

Can't post? Read http://www.gromacs.org/mailing_lists/users.php


--


Justin A. Lemkul
Ph.D. Candidate
ICTAS Doctoral Scholar
Department of Biochemistry
Virginia Tech
Blacksburg, VA
jalemkul[at]vt.edu | (540) 231-9080
http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin


___
gmx-users mailing listgmx-users@gromacs.org
http://www.gromacs.org/mailman/listinfo/gmx-users
Please search the archive at http://www.gromacs.org/search before posting!
Please don't post (un)subscribe requests to the list. Use the 
www interface or send it to gmx-users-requ...@gromacs.org.

Can't post? Read http://www.gromacs.org/mailing_lists/users.php


[gmx-users] protein falls apart in energy minimization

2009-05-11 Thread Zhong Zheng

hi all

I am running Gromacs on a protein consisted of three chains. But no  
matter how I tried, the protein always falls into three parts  
(corresponding to each chain) after a simple 2000 steps energy  
minimization. Can anyone help me please? Thanks.


Zhong Zheng
___
gmx-users mailing listgmx-users@gromacs.org
http://www.gromacs.org/mailman/listinfo/gmx-users
Please search the archive at http://www.gromacs.org/search before posting!
Please don't post (un)subscribe requests to the list. Use the 
www interface or send it to gmx-users-requ...@gromacs.org.

Can't post? Read http://www.gromacs.org/mailing_lists/users.php


Re: [gmx-users] protein falls apart in energy minimization

2009-05-11 Thread Mark Abraham

Zhong Zheng wrote:

hi all

I am running Gromacs on a protein consisted of three chains. But no 
matter how I tried, the protein always falls into three parts 
(corresponding to each chain) after a simple 2000 steps energy 
minimization. Can anyone help me please? Thanks.


Are you seeing a visualization artefact caused by periodic boundary 
conditions? You can play with trjconv on your output file to see.


Mark
___
gmx-users mailing listgmx-users@gromacs.org
http://www.gromacs.org/mailman/listinfo/gmx-users
Please search the archive at http://www.gromacs.org/search before posting!
Please don't post (un)subscribe requests to the list. Use the 
www interface or send it to gmx-users-requ...@gromacs.org.

Can't post? Read http://www.gromacs.org/mailing_lists/users.php


Re: [gmx-users] protein falls apart in energy minimization

2009-05-11 Thread Pawan Kumar
hi,

Defining a specific box size with -d option in editconf will help to
overcome this problem...

Regards,
Pawan

On Tue, May 12, 2009 at 8:05 AM, Zhong Zheng zhozh...@gmail.com wrote:

 hi all

 I am running Gromacs on a protein consisted of three chains. But no matter
 how I tried, the protein always falls into three parts (corresponding to
 each chain) after a simple 2000 steps energy minimization. Can anyone help
 me please? Thanks.

 Zhong Zheng
 ___
 gmx-users mailing listgmx-users@gromacs.org
 http://www.gromacs.org/mailman/listinfo/gmx-users
 Please search the archive at http://www.gromacs.org/search before posting!
 Please don't post (un)subscribe requests to the list. Use thewww interface
 or send it to gmx-users-requ...@gromacs.org.
 Can't post? Read http://www.gromacs.org/mailing_lists/users.php

___
gmx-users mailing listgmx-users@gromacs.org
http://www.gromacs.org/mailman/listinfo/gmx-users
Please search the archive at http://www.gromacs.org/search before posting!
Please don't post (un)subscribe requests to the list. Use the 
www interface or send it to gmx-users-requ...@gromacs.org.
Can't post? Read http://www.gromacs.org/mailing_lists/users.php