Re: [gmx-users] Failed to lock: md.log.

2013-06-14 Thread Jianguo Li
You can try move "md.log" to some folder and then copy back such as: 1) mv  md.log /some_folder 2) cp  /some_folder/md.log . It works for me Jianguo - Original Message - From: zhaowh To: gmx-users ; gmx-users ; gmx-users ; gmx-users ; gmx-users ; gmx-users Cc: Sent: Friday, 1

Re: [gmx-users] Performance of Gromacs-4.6.1 on BlueGene/Q

2013-06-04 Thread Jianguo Li
e a optimized number for --ntasks-per-node? Cheers Jianguo From: Mark Abraham To: Discussion list for GROMACS users Cc: Jianguo Li Sent: Tuesday, 4 June 2013, 22:32 Subject: Re: [gmx-users] Performance of Gromacs-4.6.1 on BlueGene/Q On Tue, Jun 4, 2

Re: [gmx-users] Performance of Gromacs-4.6.1 on BlueGene/Q

2013-06-04 Thread Jianguo Li
Job queue ( default is normal ) srun --ntasks-per-node=32 --overcommit /scratch/home/biilijg/package/gromacs-461/bin/mdrun -s box_md1.tpr -c box_md1.gro -x box_md1.xtc -g md1.log >& job_md1 Cheers Jianguo - Original Message ----- From: XAvier Periole To: Jianguo Li ; Discussi

[gmx-users] Performance of Gromacs-4.6.1 on BlueGene/Q

2013-06-04 Thread Jianguo Li
Dear All, Has anyone has Gromacs benchmark on Bluegene/Q? I recently installed gromacs-461 on BG/Q using the following command: cmake .. -DCMAKE_TOOLCHAIN_FILE=BlueGeneQ-static-XL-C \   -DGMX_BUILD_OWN_FFTW=ON \ -DBUILD_SHARED_LIBS=OFF \ -DGMX_XML=OFF \ -DCMAKE

Re: [gmx-users] keeping water (entirely) out of the bilayer core

2013-05-06 Thread Jianguo Li
Hi Chris, Just think of another possible way without modifying the code. The task can be achieved by increasing the LJ repulsion term between the lipid tail atoms and water molecules, but keeping all other interactions unchanged. To do so, the free energy code can be used. You can create a st

Re: [gmx-users] keeping water (entirely) out of the bilayer core

2013-05-04 Thread Jianguo Li
Hi Chris, Perhaps you can try PLUMED+GROMACS. In that case, you can define a collective variable as mindist between the water molecules and the lipid tails. And then apply wall potential to keep this CV above a certain value.  Jianguo From: Christopher Neale

Re: [gmx-users] fail to pull

2013-04-07 Thread Jianguo Li
You switched on the position restraint in your mdp file, is that the reason? From: Albert To: gromacs maillist Sent: Sunday, 7 April 2013, 2:47 Subject: [gmx-users] fail to pull Dear: I am trying to pull my ligand outside of the binding pocket with followin

Re: [gmx-users] Weird result of WHAM

2012-11-15 Thread Jianguo Li
If the two end states of a system are fixed, the free energy difference is independent of the path. I am not sure what caused the problem, but if besides the protein, water and ions, there are some other molecules in your simulation box (e.g., membrane or ligand), the states A and B of your prot

Re: [gmx-users] steered pulling code on ligand-receptor complex

2012-10-31 Thread Jianguo Li
If you position restraint the receptor or only use several residues at the binding site, in both cases you limit your sampling to a small part of the phase space and the PMF may not be accurate, since the receptor may undergo conformational change upon ligand binding. Cheers --Jianguo - O

Re: [gmx-users] Umbrella sampling after TMD of NAMD

2012-10-17 Thread Jianguo Li
It seems difficult to use RMSD as the reaction coordinate to do umbrella sampling simulations. Maybe you can try meta-dynamics in which you can use RMSD as a collective to get the free energy. It is implemented in a modified version of gromacs (GROMETA), or you can use PLUMED together with curr

Re: [gmx-users] When are .trr files essential? (was: Regarding Gromacs output files)

2012-10-12 Thread Jianguo Li
One situation is the analysis that require velocities, such as calculating velocity autocorrelation function or lateral pressure.  -Jianguo From: Ladasky To: gmx-users@gromacs.org Sent: Friday, 12 October 2012, 13:25 Subject: [gmx-users] When are .trr files

Re: [gmx-users] Orientation of protein

2012-09-11 Thread Jianguo Li
editconf -princ will put the long axis of the protein in x-direction, after that you may need editconf -rotate 0 90 0 -c to make it in z-direction -Jianguo - Original Message - From: Shima Arasteh To: Discussion list for GROMACS users Cc: Sent: Tuesday, 11 September 2012, 15:18 Su

Re: [gmx-users] umbrella sampling (PMF) position discrepancy

2012-09-10 Thread Jianguo Li
I guess is that g_wham takes the distance from tpr file which calculates the distance using grommp. It seems that the distances calculated using g_dist and grompp are different, as discussed in this forum about 10 days ago. -Jianguo - Original Message - From: Raphael Alhadeff To:

Re: [gmx-users] Umbrella Sampling Pull code Problem

2012-08-31 Thread Jianguo Li
I have met similar problem before. The distance calculated by g_dist is different from that calculated by grommp, especially when the actual distance between the two groups is very small. As the actual distance becomes larger, the difference of the distance from the two commands becomes smalle

Re: [gmx-users] Protein-POPC bilayer

2012-08-16 Thread Jianguo Li
the job, but I expect it may take longer time to reach equilibrium. --Jianguo From: Justin Lemkul To: Jianguo Li ; Discussion list for GROMACS users Sent: Friday, 17 August 2012, 9:19 Subject: Re: [gmx-users] Protein-POPC bilayer On 8/16/12 9:14 PM

Re: [gmx-users] Protein-POPC bilayer

2012-08-16 Thread Jianguo Li
After inserting the protein, the equilibrium box length in the x and y dimension should be different, so you need anisotropic pressure coupling during the 1st step. After equilibrium, the ratio of box length in x,y is fixed, so you can use semi-isotropic method. --Jianguo ___

Re: [gmx-users] how to build a mixed lipid bilayer?

2012-07-29 Thread Jianguo Li
There are several ways, usually I do like the following: 1. first construct one leaflet. Use "editconf -translate" to construct a small box containing with 3 POPE 1 POPE 2. Use "genconf -nbox" to replicate the above in x,y dimension to get 64 lipids 3. Use "editconf -rotate -translate" to get th

Re: [gmx-users] cutting a cylinder from simulation box

2012-02-27 Thread Jianguo Li
Maybe you can try "trjorder" to order the water molecules around your protein and make a group of those nearest water molecules and output them using trjconv Jianguo From: Sanku M To: Discussion list for GROMACS users Sent: Tuesday, 28 February 2012, 7:49 Su

Re: [gmx-users] Free energy between surfaces

2012-02-18 Thread Jianguo Li
One way to get the free energy is to measure the force as a function of distance and do the integration to get the PMF, as used in the paper: Ronen Zangi, Morten Hagen, and B. J. Berne. 2007. Effect of Ions on the Hydrophobic Interaction betweenTwo Plates. J. AM. CHEM. SOC. 2007, 129, 4678-468

Re: [gmx-users] the ligang topology

2012-02-15 Thread Jianguo Li
This paper has used united atoms for -CF3 and -CF2: Hiroaki et al. Enhanced Hydrophobicity of Fluorinated Lipid Bilayer: A Molecular Dynamics Study. J. Phys. Chem. B 2008, 112, 11305–11309. Another way is to use ATB to generate the topology, but I am not sure if it can deal with fluorine atom

Re: [gmx-users] Water Shell Density

2012-02-15 Thread Jianguo Li
Probably you can use g_rdf -surf to get the surface based g(r) for water molecules, since g(r) is the local_density divided by the average_density, then local_density=g(r)_surf*average_density, which is a function of distance from the surface. Jianguo From

Re: [gmx-users] water channel

2012-02-14 Thread Jianguo Li
You can look at gromacs tool g_flux and g_count at: https://github.com/orbeckst/g_count Jianguo From: Yao Yao To: "gmx-users@gromacs.org" Sent: Wednesday, 15 February 2012, 10:38 Subject: [gmx-users] water channel Hi Gmxers, Happy Valentine's Day! Sor

Re: [gmx-users] Orders of the residues in gromacs

2012-02-02 Thread Jianguo Li
Another possible reason is due to vmd, which numbers the residue from 0. Residue 143 in gromacs corresponds to residue 142 in vmd. Cheers, Jianguo From: Du Jiangfeng (BIOCH) To: "gmx-users@gromacs.org" Sent: Friday, 3 February 2012, 1:16 Subject: [gmx-users

Re: [gmx-users] Failed to lock: md.log. No locks available.

2012-01-13 Thread Jianguo Li
There is a solution in this mailing list sometime before: mv md.log to some other folder and copy it back. Jianguo From: lina To: Discussion list for GROMACS users Sent: Friday, 13 January 2012, 18:51 Subject: Re: [gmx-users] Failed to lock: md.log. No lock

Re: [gmx-users] CMAP for alanine dipeptide in Charmm27 ff

2011-10-10 Thread Jianguo Li
dipeptide in Charmm27 ff To: "Jianguo Li" , "Discussion list for GROMACS users" Date: Monday, 10 October, 2011, 5:51 PM v4.5.4 As I commented above, I had to manually add an entrance for the cmap terms in the topology file as pdb2gmx would not generate them for the alanine dipept

Re: [gmx-users] CMAP for alanine dipeptide in Charmm27 ff

2011-10-10 Thread Jianguo Li
which gromacs version are you using? cMAP is implemented in v4.5  or later Jianguo From: César Ávila To: Discussion list for GROMACS users Sent: Sunday, 9 October 2011 12:07 AM Subject: [gmx-users] CMAP for alanine dipeptide in Charmm27 ff I would like to ru

Re: [gmx-users] Re: about non-writing issue

2011-09-18 Thread Jianguo Li
I met the similar problem before, sometimes my job writes output, sometimes not. My cluster administrator fixed the problem and they told me that there were some problem at some compute nodes which my job unfortunately was dispatched to. Jianguo From: lina

Re: [gmx-users] residue numbering different

2011-09-15 Thread Jianguo Li
The first residue number in VMD is 0, not 1. Jianguo From: aiswarya pawar To: Discussion list for GROMACS users Sent: Friday, 16 September 2011 1:21 PM Subject: [gmx-users] residue numbering different Hi Users, When i list the residues in a index file it show

Re: [gmx-users] how to handle different atom names between pdb and rtp files.

2011-09-14 Thread Jianguo Li
You can either use -ighn option in pdb2gmx or mannualy rename the atom names in the pdb file. Cheers, Jianguo From: KONG Xian To: gmx-users@gromacs.org Sent: Tuesday, 13 September 2011 15:36:41 Subject: [gmx-users] how to handle different atom names between

Re: [gmx-users] Error when performing grompp on lipid bilayer modeled with CHARMM27

2011-09-05 Thread Jianguo Li
Why not use CHARMM36 FF? It is available in gromacs user contribution website. If I remember correctly, charmm27 cannot yield correct area/lipid, you need to apply surface tension. Cheeers, Jianguo From: Jackson Chief To: gmx-users@gromacs.org Sent: Monday, 5

Re: [gmx-users] Convert drug Charmm topology to Gromacs

2011-08-24 Thread Jianguo Li
Hi, The .str file contains the information of atomtype, bonds and improper dihedrals, so it is eneough to write a .rtp file. Then using pdb2gmx to generate the itp file. And you also need to add the missing parameters from CgenFF into the itp parameter files based on chapter 5, as Justin sug

Re: [gmx-users] error:You might need to add atom H to the hydrogen database of residue

2011-08-24 Thread Jianguo Li
error. From: gmx-users-boun...@gromacs.org [gmx-users-boun...@gromacs.org] On Behalf Of Jianguo Li [ljg...@yahoo.com.sg] Sent: Wednesday, August 24, 2011 3:06 PM To: Discussion list for GROMACS users Subject: Re: [gmx-users] error:You might need to add atom H t

Re: [gmx-users] error:You might need to add atom H to the hydrogen database of residue

2011-08-24 Thread Jianguo Li
you may need to use -ignh option in pdb2gmx. Jianguo From: Kamesh Narasimhan To: "gmx-users@gromacs.org" Sent: Wednesday, 24 August 2011 14:42:28 Subject: [gmx-users] error:You might need to add atom H to the hydrogen database of residue Hi all, I a

[gmx-users] Re: Re:the mdp parameters for localpressure calculation using gromacs-4.0.2_localpressure

2011-08-21 Thread Jianguo Li
From: KONG Xian To: ljg...@yahoo.com.sg Cc: gmx-users@gromacs.org Sent: Sunday, 21 August 2011 19:20:50 Subject: Re:the mdp parameters for localpressure calculation using gromacs-4.0.2_localpressure Thanks for your kindly reply. I used the LINCS calculate

Re: [gmx-users] the mdp parameters for localpressure calculation using gromacs-4.0.2_localpressure

2011-08-20 Thread Jianguo Li
Hi, Kong Xian, It is better to use SHAKE instead of LINCS since LINCS does not directly yield pairwise forces, as shown in the paper: Erik Lindahl and Olle Edholm. Spatial and energetic-entropic decomposition of surface tension in lipid bilayers from molecular dynamics simulations. JOURNAL OF CH

Re: [gmx-users] Re: local pressure v4.5 issues

2011-07-28 Thread Jianguo Li
I have tried CHARMM FF in v4.0.4 and it does not give error, so it seems dihedral type 9 has already been implemented in v4.0.4. Jianguo From: Jianguo Li To: Amit Choubey Cc: Discussion list for GROMACS users Sent: Thursday, 28 July 2011 15:05:19 Subject

Re: [gmx-users] Re: local pressure v4.5 issues

2011-07-28 Thread Jianguo Li
Use grompp of v4.0.7 to generate the tpr files using CHARMM FF and give this tpr file to v4.0.2_local_pressure to rerun the simulation. Jianguo From: Amit Choubey To: Jianguo Li Cc: Discussion list for GROMACS users Sent: Thursday, 28 July 2011 09:27:04

Re: [gmx-users] How to exert different lateral pressure profile of a membrane to study its influence on a protein inserted in the double layer membrane?

2011-07-26 Thread Jianguo Li
Lateral pressure is a function of z-distance, maybe you can try simulations using different surface tension, which is the integration of lateral pressure. Cheers, Jianguo From: KONG Xian To: gmx-users@gromacs.org Sent: Wednesday, 27 July 2011 10:58:56 Subje

Re: [gmx-users] REMD with 'bad contacts' error

2011-07-05 Thread Jianguo Li
One thing you can try in your membrane simulation is to couple the Protein, Lipid and Water_Ion separately to the thermal bath. Cheers, Jianguo From: Sheeba Jem To: gmx-users@gromacs.org Sent: Wednesday, 6 July 2011 07:05:43 Subject: [gmx-users] REMD with 'b

Re: [gmx-users] Energy-groups?

2011-07-01 Thread Jianguo Li
You can specify the energygrps in mdp file, grompp a new tpr file and use -rerun option of the mdrun to get a new edr file Cheers Jianguo From: "nishap.pa...@utoronto.ca" To: gmx-users@gromacs.org Sent: Tuesday, 7 December 2010 02:56:04 Subject: [gmx-user

Re: [gmx-users] Re: local pressure v4.5 issues

2011-06-30 Thread Jianguo Li
k you very much! Cheers, Jianguo From: Amit Choubey To: Jianguo Li Cc: Discussion list for GROMACS users Sent: Friday, 1 July 2011 11:47:58 Subject: Re: [gmx-users] Re: local pressure v4.5 issues On Thu, Jun 30, 2011 at 7:57 PM, Jianguo Li wrote: Hi

Re: [gmx-users] Re: local pressure v4.5 issues

2011-06-30 Thread Jianguo Li
s. Btw, did you use CHARMM FF in your simulations and how did you convert the tpr files from v 4.5 to v 4.0? Cheers Jianguo From: Amit Choubey To: Jianguo Li ; Discussion list for GROMACS users Sent: Friday, 1 July 2011 10:32:07 Subject: Re: [gmx-users]

Re: [gmx-users] Re: local pressure v4.5 issues

2011-06-22 Thread Jianguo Li
Choubey To: Jianguo Li ; Discussion list for GROMACS users Sent: Wednesday, 22 June 2011 00:16:43 Subject: Re: [gmx-users] Re: local pressure v4.5 issues On Tue, Jun 21, 2011 at 1:13 AM, Jianguo Li wrote: Hi Amit, > >May I ask you a question? >In your calculation of local pressur

Re: [gmx-users] local pressure calcuation for Gromacs-4.5

2011-06-15 Thread Jianguo Li
Dear all, I have made a test calculation of local pressure using version 4.5 for my membrane simulation using CHARMM FF. When rerun the simulation, mdrun gives the localpressure data. Howeve, instead of giving an anveraged data of the local pressure, mdrun gives a separate file for each frame,

Re: [gmx-users] gmx4.5.4 installation help

2011-06-02 Thread Jianguo Li
The error message already shows some hints. Try recompile FFTW with -fPIC. Jianguo From: Chandan Choudhury To: gmx-users Sent: Thursday, 2 June 2011 15:03:03 Subject: [gmx-users] gmx4.5.4 installation help Hello gmx-users, I am trying to install gmx-4.5.4

Re: [gmx-users] Gravity force in equation of motion

2011-06-01 Thread Jianguo Li
Seems gravity is much weaker than the other forces in molecular simulations and thus can be neglected. Jianguo From: mohsen ramezanpour To: Discussion list for GROMACS users Sent: Wednesday, 1 June 2011 15:20:09 Subject: [gmx-users] Gravity force in equation

Re: Re: Re: [gmx-users] is it possible to convert NAMD psf file to gromacas format?

2011-05-29 Thread Jianguo Li
I equilibrated the system for about 20ns at 300K. Jianguo From: albert To: Jianguo Li Cc: Discussion list for GROMACS users Sent: Monday, 30 May 2011 14:52:23 Subject: Re:Re: Re: [gmx-users] is it possible to convert NAMD psf file to gromacas format

[gmx-users] Improper dihedrals in Charmm FF

2011-04-21 Thread Jianguo Li
Dear all, My molecule contains -CH=CH- fragment and I am trying to create the topology using Charmm FF. It seems that there is no improper dihedrals for -CH=CH- fragment in Charmm FF, while other FF (e.g., Amber or OPLS) has additional improper dihedrals terms for that fragment. Could anybody

Re: [gmx-users] C-terminal amidation of peptide

2011-03-20 Thread Jianguo Li
If you use CHARMM FF and Gromacs4.5 or later, you can use -ter in pdb2gmx and choose CT2 to add NH2 at C-terminus. For other FF, you may need to manually add NH2 in pdb file. Jianguo From: anna Kalkbrenner To: gmx-users@gromacs.org Sent: Sunday, 20 March 2

Re: [gmx-users] Re: g_hbond output

2011-03-16 Thread Jianguo Li
tion, since there is already one bond formed, then why there is none pairs in 1000? On Wed, Mar 16, 2011 at 3:16 PM, Jianguo Li wrote: If I understand correctly, $2 is the number of hydrogen bonds defined by cutoff distance and the cutoff angle. $3 is the number of pairs within the cutoff dist

Re: [gmx-users] Re: g_hbond output

2011-03-16 Thread Jianguo Li
If I understand correctly, $2 is the number of hydrogen bonds defined by cutoff distance and the cutoff angle. $3 is the number of pairs within the cutoff distance, but beyond the cutoff angle. You may got different number of hbonds using different cutoff distance and cutoff angle. Jianguo __

Re: [gmx-users] Zero Potential of Mean Force with g_wham

2011-03-09 Thread Jianguo Li
I met the same problem when using 4.5.1 for some systems, the PMF shows zero curve, while the hist file looks fine. The problem disappears when using 4.5.2. Jianguo From: Susana Tomasio To: gmx-users@gromacs.org Sent: Wednesday, 9 March 2011 20:07:25 Subject:

Re: [gmx-users] parallel running

2011-03-08 Thread Jianguo Li
You don't use qsub or bsub? usually you should submit a script file containing the gromacs command, then bsub/qsub will allocate the required resource to your job. Jianguo From: mohsen ramezanpour To: Discussion list for GROMACS users Sent: Tuesday, 8 March

Re: [gmx-users] Re: adding ff parameter of modified residue to charmm ff

2011-03-03 Thread Jianguo Li
My way of doing it is: (1) add two new residues entries (with two different names) for glycine and seine in the rtp file and corresponding FF files. The new entries in the rtp file for glycine and serine should have the same number of atoms as in the real molecule (delete the unnecessary H o

[gmx-users] REMD simulation of peptide-membrane system

2011-03-03 Thread Jianguo Li
Dear all, I'd like to do folding simulations of a short peptide on membrane surface using REMD using atomistic FF. But the problem is that membrane will disrupt at high temperatures. To maintain the membrane structure, I am thinking the following two methods: (1) To use different coupling temp

Re: [gmx-users] Can g_wham support using different temperature for different windows?

2011-02-23 Thread Jianguo Li
Sent: Wednesday, 23 February 2011 20:59:18 Subject: Re: [gmx-users] Can g_wham support using different temperature for different windows? On Feb 23, 2011, at 3:21 AM, Jianguo Li wrote: >Thank you  for the the useful information, XAvier. >My peptide is highly positively charged, 18 AA wi

Re: [gmx-users] Can g_wham support using different temperature for different windows?

2011-02-23 Thread Jianguo Li
l conformation (e.g. 10.1016/j.bpj.2010.12.3682). It is anyway a very difficult problem (and probably impossible at atomistic resolution) to get a converged PMF for a whole peptide (e.g. 10.1016/j.bpj.2009.03.059). Ciao, Patrick Le 23/02/2011 05:25, Jianguo Li a écrit : > Sorry, why do you

Re: [gmx-users] Can g_wham support using different temperature for different windows?

2011-02-22 Thread Jianguo Li
temperature for different windows? Jianguo Li wrote: > Thank you, Justin. > Actually I did windowed umbrella simulations from d=-1.05nm to d=9nm. Since I >think there is no problem in the region out of the membrane, so I only show >the >configurations within the membrane. My objectiv

Re: [gmx-users] Can g_wham support using different temperature for different windows?

2011-02-22 Thread Jianguo Li
lices up to 8 us ... and no charges were involved. This might be a lot pessimistic but you should not get fooled by a CG model. Martini is really good for a lot of things but other things should really but be looked at carefully. XAvier. On Feb 22, 2011, at 9:12 AM, Jianguo Li wrote: Sorry I fo

Re: [gmx-users] Can g_wham support using different temperature for different windows?

2011-02-22 Thread Jianguo Li
windows. Cheers Jianguo From: Justin A. Lemkul To: Gromacs Users' List Sent: Tuesday, 22 February 2011 21:10:08 Subject: Re: [gmx-users] Can g_wham support using different temperature for different windows? Jianguo Li wrote: > Thanks Justin and C

Re: [gmx-users] Can g_wham support using different temperature for different windows?

2011-02-22 Thread Jianguo Li
ianguo From: Jianguo Li To: jalem...@vt.edu; Discussion list for GROMACS users Sent: Tuesday, 22 February 2011 14:27:34 Subject: Re: [gmx-users] Can g_wham support using different temperature for different windows? Thanks Justin and Chris and sorry for con

Re: [gmx-users] Can g_wham support using different temperature for different windows?

2011-02-21 Thread Jianguo Li
From: Justin A. Lemkul To: Gromacs Users' List Sent: Tuesday, 22 February 2011 11:13:05 Subject: Re: [gmx-users] Can g_wham support using different temperature for different windows? Jianguo Li wrote: > Thanks for your comments, Justin. > > Using timestep of

Re: [gmx-users] Can g_wham support using different temperature for different windows?

2011-02-21 Thread Jianguo Li
09:58:36 Subject: Re: [gmx-users] Can g_wham support using different temperature for different windows? Jianguo Li wrote: > Thanks Justin. > I tried your suggestions by either increase more windows and change the force >constant, but it seems the samplings are still bad in some windo

Re: [gmx-users] Can g_wham support using different temperature for different windows?

2011-02-21 Thread Jianguo Li
GROMACS users Sent: Tuesday, 22 February 2011 09:35:37 Subject: Re: [gmx-users] Can g_wham support using different temperature for different windows? Jianguo Li wrote: > Dear all, > > I want to get the PMF of my peptide across the membrane bilayer. First I > pulled >my peptide acro

[gmx-users] Can g_wham support using different temperature for different windows?

2011-02-21 Thread Jianguo Li
Dear all, I want to get the PMF of my peptide across the membrane bilayer. First I pulled my peptide across the membrane and then did windowed umbrella sampling along the reaction coordinates which is the z-distance between peptide and membrane. However, I found that sampling is not sufficient

Re: [gmx-users] Protein-membrane system

2011-02-16 Thread Jianguo Li
Hi, "3000 water molecule per lipids per second" corresponds to 0.000384 water molecules transferred across the membrane per nano second (assume the system contains 128 lipids). It seems water translocation should not be observed in a simulation of 10 ns, but I am not sure. And I only find one r

[gmx-users] local pressure calcuation for Gromacs-4.5

2011-01-27 Thread Jianguo Li
Hi All, I found there is a customised version "gromacs-4.0.2_localpressure" for calculating the local pressure from the Gromacs website. I am wondering is there a higher version? The reason is that I am using CHARMM FF and have done membrane simulations using Gromacs-4.5. If I understand cor

[gmx-users] box length in z dimension keep increasing when using two walls in NPT ensemble

2010-12-11 Thread Jianguo Li
Dear all, I was trying to add two walls at z=0 and z=z_box to my system which contains one peptide and one membrane. Since I am interested in how the peptides affect membrane properties (i.e., area per lipid), I need to use semi-isotropic pressure coupling. But I wanted to mimick the two-dimen

[gmx-users] questions about long-range electrostatic interaction in membrane systems

2010-12-06 Thread Jianguo Li
Dear All, I am working on the interaction of a positively charged peptide (18AA) and the bacterial membrane consisting of a mixture of zitterionic and negatively charged lipids. Our experiments show that the peptide can disrutp the membrane. One problem puzzed me is that which method to use i