RE: [gmx-users] Overflow problem with test-particle insertion

2010-09-09 Thread Berk Hess
Hi, This is an interesting issue. The chance is quite small that this happens, but maybe not negligible. In single precision the maximum a float can store is 2^127. This gives a minimum distance of (2^127)^-1/12 = 6.5e-4 nm. The chance of inserting a particle within this radius is dens*3e-10, whe

Re: [gmx-users] Re: multiplication of lambda constant with LJ potential affecting only solvent.

2010-09-09 Thread Mark Abraham
- Original Message - From: Navjeet Ahalawat Date: Thursday, September 9, 2010 16:56 Subject: [gmx-users] Re: multiplication of lambda constant with LJ potential affecting only solvent. To: gmx-users@gromacs.org > Hi all > > I want to change LJ potential for water only by multiplying a

Re: [gmx-users] restraining atoms to the plane at the bilayer center: pull code ?

2010-09-09 Thread maria goranovic
Hmm. I am getting the desired output now, at least as far as the pulled atoms are concerned, they are all close to the bilayer center (was not so in a free simulation), and therefore my suspicion is that the code is working. Just to re-iterate, the atoms to be pulled to the bilayer center were pre

[gmx-users] How to select atoms dynamically

2010-09-09 Thread zhongjin
Dear Elton,        Of course, I happy to discuss some questions about CNT in GROMACS. My Email is zhongjin1...@yahoo.com.cn  Zhongjin He -- gmx-users mailing listgmx-users@gromacs.org http://lists.gromacs.org/mailman/listinfo/gmx-users Please search the archive at http://www.gromacs.

[gmx-users] About implicit water simulations

2010-09-09 Thread Christian Mücksch
Dear users, I got a question concerning simulations with implicit solvent. So far it is only possible to use this model when applying a cut-off for the long range electrostatic and vdW interactions which leads to bad energy conservation etc. Will there be an update allowing to use reaction-

Re: [gmx-users] About implicit water simulations

2010-09-09 Thread Per Larsson
Hi! This is not something that is planned for the immediate future, as useful as it might be. However, for small to medium sized systems one can get good performance by using the all-vs-all kernels. Then the problem of poor energy conservation disappears. Cheers /Per Skickat från min iPhon

RE: [gmx-users] Overflow problem with test-particle insertion

2010-09-09 Thread Berk Hess
Hi, I realized now that this is an SSE issue. Normally you would get NAN (or is it INF?). That is treated correctly in the GROMACS TPI code. But in SSE a float "wraps around" when it overflows, which could, in very few cases, lead to a reasonably looking energy value (I check for very high and

[gmx-users] selected forces

2010-09-09 Thread Ali Hassanali
Dear Gromacs Users, I've read through various posts on a related issue but am hoping that someone will have some ideas on this or at least point me in the right direction. I am also hoping that some discussion on this will help develop some routines that would allow users to approach this prob

[gmx-users] pdb2gmx gmx 4.5: issues with atom name in last column

2010-09-09 Thread Alan
Hi there, when using for example: pdb2gmx -f aQQQ.pdb -o agQQQ.pdb -p agQQQ.top -ff amber99sb -water none I got in the agQQQ.pdb, things like: ATOM 15 NE2 NGL 1 4.309 7.159 2.648 1.00 0.00 N ATOM 16 1HE2 NGL 1 4.030 7.698 3.448 1.00 0.00 HE ATOM 17

[gmx-users] Re: reg Mopac gromacs compilation problem

2010-09-09 Thread Vitaly Chaban
Hello, vidhya sankar - If the env. var's are really set and operate correctly, one should look for the problem in the MOPAC library itself. Do you use precompiled libmopac.a or compile it by hand? BTW, did you try to exactly follow the procedure described on my website, from the very beginning??

[gmx-users] mdyn/A to kJ/mol rad2

2010-09-09 Thread Nilesh Dhumal
Hello, I want to convert force constant from mdyn/A to kJ/mol rad2. How to convert mdyn/A to kJ/mol rad2 Thanks NIlesh -- gmx-users mailing listgmx-users@gromacs.org http://lists.gromacs.org/mailman/listinfo/gmx-users Please search the archive at http://www.gromacs.org/Support/Mailing_Li

[gmx-users] res_com in g_rdf

2010-09-09 Thread Emily Curtis
Hi. I am running simulations with DPPC and water molecules. I made groups from a set of atoms from each DPPC molecule (example: Group 1 = C1, C2, C3 Group 2 = C4, C5, C6). I want to calculate the rdf for the center of mass of each group from each DPPC molecule while excluding groups located o

Re: [gmx-users] pdb2gmx gmx 4.5: issues with atom name in last column

2010-09-09 Thread David van der Spoel
On 2010-09-09 18.37, Alan wrote: Hi there, when using for example: pdb2gmx -f aQQQ.pdb -o agQQQ.pdb -p agQQQ.top -ff amber99sb -water none I got in the agQQQ.pdb, things like: ATOM 15 NE2 NGL 1 4.309 7.159 2.648 1.00 0.00 N ATOM 16 1HE2 NGL 1 4.030 7.

[gmx-users] Amber force fields giving LINCS errors

2010-09-09 Thread TJ Mustard
First off I am using gromacs 4.5. I will also post all of my files and errors if they help.   If I run a protein in GROMOS96 all my md runs complete succesfully. But if I change to any of the AMBER force fields I get LINCS errors in my positional restraint md run

[gmx-users] tip5p.itp in Charmm

2010-09-09 Thread Yao Yao
Hi, I am running charmmm force field (ff) in gmx 4.5 version and just trying on tip5p water model in it. Unfortunately I only find tip5p.gro is in the ff, not tip5p.itp file. Can anyone help me with hints on constructing it? Many thanks, Yao -- gmx-users mailing listgmx-users

Re: [gmx-users] Amber force fields giving LINCS errors

2010-09-09 Thread Justin A. Lemkul
TJ Mustard wrote: First off I am using gromacs 4.5. I will also post all of my files and errors if they help. If I run a protein in GROMOS96 all my md runs complete succesfully. But if I change to any of the AMBER force fields I get LINCS errors in my positional restraint md run. I hav

Re: [gmx-users] Amber force fields giving LINCS errors

2010-09-09 Thread TJ Mustard
Of course. I am trying to run the ribosome 30s subunit on gromax 4.5. I chose the AMBER force field since it had the least issues with RNA and that made running pdb2gmx much easier. Everything is fine till I run a md. Below I have attached everything I think is informativ

Re: [gmx-users] Amber force fields giving LINCS errors

2010-09-09 Thread TJ Mustard
My one thought is that it is to large of a system for GROMACS to run it, yet I have run a small protein in GROMOS96-43a1 and it works but not in any of the AMBER force fields. On September 9, 2010 at 9:35 PM TJ Mustard wrote: Of course

Re: [gmx-users] Overflow problem with test-particle insertion

2010-09-09 Thread Javier Cerezo
Hello. Probably that will not be related with the original problem but that's something that came to me when reviewing the tpi.c code: In line 583 (and follow), it is stated: if (epot != epot || epot*beta < bU_neg_limit) { if (debug)

Re: [gmx-users] Amber force fields giving LINCS errors

2010-09-09 Thread Justin A. Lemkul
TJ Mustard wrote: *Positional restraint mdp file:* define = -DPOSRES constraints = all-bonds integrator = md dt = 0.004 ; ps Unless you're using virtual sites (which, per your commands below, you are not) this time step i

Re: [gmx-users] mdyn/A to kJ/mol rad2

2010-09-09 Thread Mark Abraham
- Original Message - From: Nilesh Dhumal Date: Friday, September 10, 2010 4:41 Subject: [gmx-users] mdyn/A to kJ/mol rad2 To: gmx-users@gromacs.org > Hello, > I want to convert force constant from mdyn/A to kJ/mol rad2. > How to convert mdyn/A to kJ/mol rad2 So what's the definition of

Re: [gmx-users] Amber force fields giving LINCS errors

2010-09-09 Thread TJ Mustard
On September 9, 2010 at 10:04 PM "Justin A. Lemkul" wrote: > > > TJ Mustard wrote: > > > > > *Positional restraint mdp file:* > > > >  > > > > define                  = -DPOSRES > > constrain

Re: [gmx-users] GFP Simulation

2010-09-09 Thread Veera Krasnenko
> Dear Gmxers, > > I am working on a new project and I plan to do some molecular dynamic > simulation on an engineered GFP molecule. I have been searching for the > parameters for the GFP chromophore without success. Could some one help > me? Any > reference or parameters will be appreciated. Nath

RE: [gmx-users] Overflow problem with test-particle insertion

2010-09-09 Thread Kevin Daly
Hi, Thank you for taking the time to fix the issue. I would be very interested in testing out the modified code, but unfortunately I have had some difficulties compiling the Gromacs code obtained straight from GIT. In particular, I encounter the following error: ~/gromacs/src/tools/gmx_membed.c:1

Re: [gmx-users] tip5p.itp in Charmm

2010-09-09 Thread Mark Abraham
- Original Message - From: Yao Yao Date: Friday, September 10, 2010 6:05 Subject: [gmx-users] tip5p.itp in Charmm To: gmx-users@gromacs.org > Hi, > > I am running charmmm force field (ff) in gmx 4.5 version and > just trying on tip5p water model in it. Unfortunately I only > find tip

Re: [gmx-users] tip5p.itp in Charmm

2010-09-09 Thread Mark Abraham
- Original Message - From: Mark Abraham Date: Friday, September 10, 2010 8:59 Subject: Re: [gmx-users] tip5p.itp in Charmm To: Discussion list for GROMACS users > > > - Original Message - > From: Yao Yao > Date: Friday, September 10, 2010 6:05 > Subject: [gmx-users] tip5p.it

[gmx-users] Overflow problem with test-particle insertion

2010-09-09 Thread Kevin Daly
Hi, Thank you for taking the time to fix the issue. I would be very interested in testing out the modified code, but unfortunately I have had some difficulties compiling the Gromacs code obtained straight from GIT. In particular, I encounter the following error: ~/gromacs/src/tools/gmx_ membed.c:

[gmx-users] Overflow problem with test-particle insertion

2010-09-09 Thread Kevin Daly
Hi, Thank you for taking the time to fix the issue. I would be very interested in testing out the modified code, but unfortunately I have had some difficulties compiling the Gromacs code obtained straight from GIT. In particular, I encounter the following error: ~/gromacs/src/tools/gmx_membed.c:1

Re: [gmx-users] selected forces

2010-09-09 Thread Mark Abraham
- Original Message - From: Ali Hassanali Date: Friday, September 10, 2010 2:21 Subject: [gmx-users] selected forces To: gmx-users@gromacs.org > Dear Gromacs Users, > > I've read through various posts on a related issue but am hoping > that someone will have some ideas on this or at le

[gmx-users] parallel run problem for nwall

2010-09-09 Thread Yi Gao
Dear Sir, I am using nwall to run my system. My version is Gromacs 4.0.7. Interestingly, I could parallel run my system on 1 node with 4 or 8 cpus, but when I run it on multi-node PC-cluster, it always fails and gives no message at all. I wonder if you could help me to resolve this problem? Thanks

Re: [gmx-users] parallel run problem for nwall

2010-09-09 Thread Mark Abraham
- Original Message - From: Yi Gao Date: Friday, September 10, 2010 12:23 Subject: [gmx-users] parallel run problem for nwall To: gmx-users@gromacs.org > Dear Sir, > > I am using nwall to run my system. My version is Gromacs > 4.0.7. Interestingly, I could parallel run my system on 1

Re: [gmx-users] parallel run problem for nwall

2010-09-09 Thread Yi Gao
Gromacs is running well on multi-nodes without nwall. But with nwall, it doesn't work. Yi On Thu, Sep 9, 2010 at 9:28 PM, Mark Abraham wrote: > > > - Original Message - > From: Yi Gao > Date: Friday, September 10, 2010 12:23 > Subject: [gmx-users] parallel run problem for nwall > To: gmx-