Re: [gmx-users] Can we set the number of pure PME nodes when using GPUCPU?
Hi, When we used 2 GPU nodes (each has 2 cpus and 2 gpus) to do a mdrun(with no PME-dedicated node), we noticed that when CPU are doing PME, GPU are idle, that is they are doing their work sequentially. Is it supposed to be so? Is it the same reason as GPUs on PME-dedicated nodes won't be used during a run like you said before? So if we want to exploit our hardware, we should map PP-PME ranks manually, right? Say, use one node as PME-dedicated node and leave the GPUs on that node idle, and use two nodes to do the other stuff. How do you think about this arrangement? Theo On 8/22/2014 7:20 PM, Mark Abraham wrote: Hi, Because no work will be sent to them. The GPU implementation can accelerate domains from PP ranks on their node, but with an MPMD setup that uses dedicated PME nodes, there will be no PP ranks on nodes that have been set up with only PME ranks. The two offload models (PP work - GPU; PME work - CPU subset) do not work well together, as I said. One can devise various schemes in 4.6/5.0 that could use those GPUs, but they either require * each node does both PME and PP work (thus limiting scaling because of the all-to-all for PME, and perhaps making poor use of locality on multi-socket nodes), or * that all nodes have PP ranks, but only some have PME ranks, and the nodes map their GPUs to PP ranks in a way that is different depending on whether PME ranks are present (which could work well, but relies on the DD load-balancer recognizing and taking advantage of the faster progress of the PP ranks that have better GPU support, and requires that you get very dirty hands laying out PP and PME ranks onto hardware that will later match the requirements of the DD load balancer, and probably that you balance PP-PME load manually) I do not recommend the last approach, because of its complexity. Clearly there are design decisions to improve. Work is underway. Cheers, Mark On Fri, Aug 22, 2014 at 10:11 AM, Theodore Si sjyz...@gmail.com wrote: Hi Mark, Could you tell me why that when we are GPU-CPU nodes as PME-dedicated nodes, the GPU on such nodes will be idle? Theo On 8/11/2014 9:36 PM, Mark Abraham wrote: Hi, What Carsten said, if running on nodes that have GPUs. If running on a mixed setup (some nodes with GPU, some not), then arranging your MPI environment to place PME ranks on CPU-only nodes is probably worthwhile. For example, all your PP ranks first, mapped to GPU nodes, then all your PME ranks, mapped to CPU-only nodes, and then use mdrun -ddorder pp_pme. Mark On Mon, Aug 11, 2014 at 2:45 AM, Theodore Si sjyz...@gmail.com wrote: Hi Mark, This is information of our cluster, could you give us some advice as regards to our cluster so that we can make GMX run faster on our system? Each CPU node has 2 CPUs and each GPU node has 2 CPUs and 2 Nvidia K20M Device Name Device Type Specifications Number CPU NodeIntelH2216JFFKRNodesCPU: 2×Intel Xeon E5-2670(8 Cores, 2.6GHz, 20MB Cache, 8.0GT) Mem: 64GB(8×8GB) ECC Registered DDR3 1600MHz Samsung Memory 332 Fat NodeIntelH2216WPFKRNodesCPU: 2×Intel Xeon E5-2670(8 Cores, 2.6GHz, 20MB Cache, 8.0GT) Mem: 256G(16×16G) ECC Registered DDR3 1600MHz Samsung Memory20 GPU NodeIntelR2208GZ4GC CPU: 2×Intel Xeon E5-2670(8 Cores, 2.6GHz, 20MB Cache, 8.0GT) Mem: 64GB(8×8GB) ECC Registered DDR3 1600MHz Samsung Memory 50 MIC NodeIntelR2208GZ4GC CPU: 2×Intel Xeon E5-2670(8 Cores, 2.6GHz, 20MB Cache, 8.0GT) Mem: 64GB(8×8GB) ECC Registered DDR3 1600MHz Samsung Memory 5 Computing Network SwitchMellanox Infiniband FDR Core Switch 648× FDR Core Switch MSX6536-10R, Mellanox Unified Fabric Manager 1 Mellanox SX1036 40Gb Switch 36× 40Gb Ethernet Switch SX1036, 36× QSFP Interface 1 Management Network Switch Extreme Summit X440-48t-10G 2-layer Switch 48× 1Giga Switch Summit X440-48t-10G, authorized by ExtremeXOS 9 Extreme Summit X650-24X 3-layer Switch 24× 10Giga 3-layer Ethernet Switch Summit X650-24X, authorized by ExtremeXOS1 Parallel StorageDDN Parallel Storage System DDN SFA12K Storage System 1 GPU GPU Accelerator NVIDIA Tesla Kepler K20M70 MIC MIC Intel Xeon Phi 5110P Knights Corner 10 40Gb Ethernet Card MCX314A-BCBTMellanox ConnextX-3 Chip 40Gb Ethernet Card 2× 40Gb Ethernet ports, enough QSFP cables 16 SSD Intel SSD910Intel SSD910 Disk, 400GB, PCIE 80 On 8/10/2014 5:50 AM, Mark Abraham wrote: That's not what I said You can set... -npme behaves the same whether or not GPUs are in use. Using separate ranks for PME caters to trying to minimize the cost of the all-to-all communication of the 3DFFT. That's still relevant when using GPUs, but if separate PME ranks are used, any GPUs on nodes that only have PME ranks are left idle. The most effective approach depends critically on the hardware and simulation setup, and whether you pay money for
Re: [gmx-users] Can we set the number of pure PME nodes when using GPUCPU?
On Sat, Aug 23, 2014 at 1:47 PM, Theodore Si sjyz...@gmail.com wrote: Hi, When we used 2 GPU nodes (each has 2 cpus and 2 gpus) to do a mdrun(with no PME-dedicated node), we noticed that when CPU are doing PME, GPU are idle, That could happen if the GPU completes its work too fast, in which case the end of the log file will probably scream about imbalance. that is they are doing their work sequentially. Highly unlikely, not least because the code is written to overlap the short-range work on the GPU with everything else on the CPU. What's your evidence for *sequential* rather than *imbalanced*? Is it supposed to be so? No, but without seeing your .log files, mdrun command lines and knowing about your hardware, there's nothing we can say. Is it the same reason as GPUs on PME-dedicated nodes won't be used during a run like you said before? Why would you suppose that? I said GPUs do work from the PP ranks on their node. That's true here. So if we want to exploit our hardware, we should map PP-PME ranks manually, right? Say, use one node as PME-dedicated node and leave the GPUs on that node idle, and use two nodes to do the other stuff. How do you think about this arrangement? Probably a terrible idea. You should identify the cause of the imbalance, and fix that. Mark Theo On 8/22/2014 7:20 PM, Mark Abraham wrote: Hi, Because no work will be sent to them. The GPU implementation can accelerate domains from PP ranks on their node, but with an MPMD setup that uses dedicated PME nodes, there will be no PP ranks on nodes that have been set up with only PME ranks. The two offload models (PP work - GPU; PME work - CPU subset) do not work well together, as I said. One can devise various schemes in 4.6/5.0 that could use those GPUs, but they either require * each node does both PME and PP work (thus limiting scaling because of the all-to-all for PME, and perhaps making poor use of locality on multi-socket nodes), or * that all nodes have PP ranks, but only some have PME ranks, and the nodes map their GPUs to PP ranks in a way that is different depending on whether PME ranks are present (which could work well, but relies on the DD load-balancer recognizing and taking advantage of the faster progress of the PP ranks that have better GPU support, and requires that you get very dirty hands laying out PP and PME ranks onto hardware that will later match the requirements of the DD load balancer, and probably that you balance PP-PME load manually) I do not recommend the last approach, because of its complexity. Clearly there are design decisions to improve. Work is underway. Cheers, Mark On Fri, Aug 22, 2014 at 10:11 AM, Theodore Si sjyz...@gmail.com wrote: Hi Mark, Could you tell me why that when we are GPU-CPU nodes as PME-dedicated nodes, the GPU on such nodes will be idle? Theo On 8/11/2014 9:36 PM, Mark Abraham wrote: Hi, What Carsten said, if running on nodes that have GPUs. If running on a mixed setup (some nodes with GPU, some not), then arranging your MPI environment to place PME ranks on CPU-only nodes is probably worthwhile. For example, all your PP ranks first, mapped to GPU nodes, then all your PME ranks, mapped to CPU-only nodes, and then use mdrun -ddorder pp_pme. Mark On Mon, Aug 11, 2014 at 2:45 AM, Theodore Si sjyz...@gmail.com wrote: Hi Mark, This is information of our cluster, could you give us some advice as regards to our cluster so that we can make GMX run faster on our system? Each CPU node has 2 CPUs and each GPU node has 2 CPUs and 2 Nvidia K20M Device Name Device Type Specifications Number CPU NodeIntelH2216JFFKRNodesCPU: 2×Intel Xeon E5-2670(8 Cores, 2.6GHz, 20MB Cache, 8.0GT) Mem: 64GB(8×8GB) ECC Registered DDR3 1600MHz Samsung Memory 332 Fat NodeIntelH2216WPFKRNodesCPU: 2×Intel Xeon E5-2670(8 Cores, 2.6GHz, 20MB Cache, 8.0GT) Mem: 256G(16×16G) ECC Registered DDR3 1600MHz Samsung Memory20 GPU NodeIntelR2208GZ4GC CPU: 2×Intel Xeon E5-2670(8 Cores, 2.6GHz, 20MB Cache, 8.0GT) Mem: 64GB(8×8GB) ECC Registered DDR3 1600MHz Samsung Memory 50 MIC NodeIntelR2208GZ4GC CPU: 2×Intel Xeon E5-2670(8 Cores, 2.6GHz, 20MB Cache, 8.0GT) Mem: 64GB(8×8GB) ECC Registered DDR3 1600MHz Samsung Memory 5 Computing Network SwitchMellanox Infiniband FDR Core Switch 648× FDR Core Switch MSX6536-10R, Mellanox Unified Fabric Manager 1 Mellanox SX1036 40Gb Switch 36× 40Gb Ethernet Switch SX1036, 36× QSFP Interface 1 Management Network Switch Extreme Summit X440-48t-10G 2-layer Switch 48× 1Giga Switch Summit X440-48t-10G, authorized by ExtremeXOS 9 Extreme Summit X650-24X 3-layer Switch 24× 10Giga 3-layer Ethernet Switch Summit X650-24X, authorized by ExtremeXOS1 Parallel StorageDDN Parallel Storage System DDN SFA12K Storage System 1 GPU GPU
[gmx-users] Time varying electric field - phase term
Dear gromacs users, I am trying to use an electric field which is varying with time. I read the previous posts and successfully generated time varying electric field with E-xt, E-yt and E-zt. but I need an electric field which has an initial phase term (ie. of the form E= E0cos(2*pi*f*t+some angle term)) where i want to specify the angle term. Most of the posts i read mentioned this angle term must be specified in the third term after E-xt. I tried it but failed to generate an initial phase. Can anyone help me with this? thanks in advance. -- Gromacs Users mailing list * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/GMX-Users_List before posting! * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists * For (un)subscribe requests visit https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or send a mail to gmx-users-requ...@gromacs.org.
[gmx-users] Plotting hydrogen bonds and salt bridges.
Dear Gromacs experts, This time I have a question not regarding Gromacs itself but rather MD analysis in general. Let's say that I want to plot the distance between water and atom of an amino acid residue forming hydrogen bond. Now, how can I do it when water is donor of this h-bond and water molecule flips during the simulation so that the acutal donor changes? If you don't get me, have a look at this screenshot: http://www.speedyshare.com/8xHDs/Zrzut-ekranu-z-2014-08-23-19-33-45.png These two plots display distance between one residue atom and two different hydrogen atoms of the same water molecule. Now I think you understand what I mean. So, is it okay to leave it like this to show that there is constant h-bond between this water residue and amino acid residue? Or should I plot it differently? Now, I have similar question regarding salt bridges. Let's say there is salt bridge between one atom carrying negative charge and arginine residue. So how to plot distance between arginine side chain and this perticular atom? Which atom(s) of arginine should I take? Thank you, Dawid Grabarek -- Gromacs Users mailing list * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/GMX-Users_List before posting! * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists * For (un)subscribe requests visit https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or send a mail to gmx-users-requ...@gromacs.org.
Re: [gmx-users] Plotting hydrogen bonds and salt bridges.
Hi Dawid, In my understanding, a hydrogen bond is considered between one set of hydrogen-donor-acceptor in Gromacs. So, when your water molecule flips and its oxygen becomes the acceptor, it is considered as a different hydrogen bond. So, the plot you have two hydrogen bonds each with differing lifetimes, one short and the other long. I think that g_hbond takes this into account. There are different ways to plot the salt-bridge distances. The criteria used by VMD makes sense to me. VMD defines a salt-bridge between two residues if *any* oxygen of the acidic residue (Asp, Glu) falls within the cut-off distance of *any* nitrogen of the basic residue (Arg, Lys, His). However, the salt bridge distance is computed between the center of mass of all the oxygen atoms in the acidic residue side chain and the center of mass of all the nitrogen atoms in the basic residue. This distance is different than the acceptance criteria for salt bridges (like you rightly recognized), but is necessary since residues like Arginine have multiple nitrogen atoms which can switch in the salt bridge formation due to thermal motion. Regards, On Sun, Aug 24, 2014 at 12:22 AM, Dawid das add...@googlemail.com wrote: Dear Gromacs experts, This time I have a question not regarding Gromacs itself but rather MD analysis in general. Let's say that I want to plot the distance between water and atom of an amino acid residue forming hydrogen bond. Now, how can I do it when water is donor of this h-bond and water molecule flips during the simulation so that the acutal donor changes? If you don't get me, have a look at this screenshot: http://www.speedyshare.com/8xHDs/Zrzut-ekranu-z-2014-08-23-19-33-45.png These two plots display distance between one residue atom and two different hydrogen atoms of the same water molecule. Now I think you understand what I mean. So, is it okay to leave it like this to show that there is constant h-bond between this water residue and amino acid residue? Or should I plot it differently? Now, I have similar question regarding salt bridges. Let's say there is salt bridge between one atom carrying negative charge and arginine residue. So how to plot distance between arginine side chain and this perticular atom? Which atom(s) of arginine should I take? Thank you, Dawid Grabarek -- Gromacs Users mailing list * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/GMX-Users_List before posting! * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists * For (un)subscribe requests visit https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or send a mail to gmx-users-requ...@gromacs.org. -- Rajat Desikan (Ph.D Scholar) Prof. K. Ganapathy Ayappa's Lab (no 13), Dept. of Chemical Engineering, Indian Institute of Science, Bangalore -- Gromacs Users mailing list * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/GMX-Users_List before posting! * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists * For (un)subscribe requests visit https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or send a mail to gmx-users-requ...@gromacs.org.
[gmx-users] Questions about 1-4 interactions in alkanes
Hi, Section 4.2 of the manual has a discussion of dihedrals. The section contains, in part, the following text: With the periodic GROMOS potential a special 1-4 LJ-interaction must be included; with the Ryckaert-Bellemans potential _for alkanes_ the 1-4 interactions must be excluded from the non-bonded list. Note: Ryckaert-Bellemans potentials are also used in e.g. the OPLS force field in combination with 1-4 interactions. You should therefore not modify topologies generated by pdb2gmx in this case. I would like to ask in particular about the statement that with the Ryckaert-Bellemans potential _for alkanes_ the 1-4 interactions must be excluded from the non-bonded list. Here are two questions about that statement: (1) Does that statement apply ONLY to the GROMOS force field, or does it apply to the OPLS-AA force field as well? (2) What is the meaning of alkanes in that statement? - (2a) Does it refer ONLY to saturated hydrocarbons, which contain only hydrogen and carbon and contain only single covalent bonds? (Examples of such molecules are butane, isobutane, pentane, isopentane, and hexane.) - (2b) Or, does it refer to ANY molecule which contains an alkyl group? (An example of such a molecule is the amino acid isoleucine. Isoleucine contains an alkyl group -- isoleucine's side chain is an isopentyl group. Does this mean that I need to EXCLUDE 1-4 interactions among hydrogens and carbons of the isopentyl group from the non-bonded list?) (3) In the OPLS-AA force field, nexcl is usually set to 3, which _initially_ excludes 1-4 interactions. However, in OPLS-AA, 1-4 interactions are explicitly specified in the [ pairs ] section; they are taken at half-strength by setting fudgeQQ = 0.5 and fudgeLJ = 0.5 in the topology. (See, for example, this helpful explanation: https://mailman-1.sys.kth.se/pipermail/gromacs.org_gmx-users/2012-December/0 77005.html .) If the statement applies to OPLS-AA in addition to GROMOS, and if the statement applies to the alkyl atoms in, e.g. isoleucine, then do I need to EXCLUDE 1-4 interactions among isoleucine's hydrogens and carbons from the [ pairs ] section? Thank you for your time! Andrew DeYoung Carnegie Mellon University -- Gromacs Users mailing list * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/GMX-Users_List before posting! * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists * For (un)subscribe requests visit https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or send a mail to gmx-users-requ...@gromacs.org.
[gmx-users] Too much PME mesh wall time.
Hi gromacs users, I met a problem with too much PME Mesh time in my simulation. The following is my time accounting. I am running my simulation on 2 nodes. Each of them has 16 CPUs and 1 Tesla K20m Nvidia GPU. And my mdrun command is ibrun /work/03002/yliu120/gromacs-5/bin/mdrun_mpi -pin on -ntomp 8 -dlb no -deffnm pi3k-wt-charm-4 -gpu_id 00. I manually turned off dlb since when it is turned on, the simulation will crash. I have reported it to both mailing lists and talked to Roland. R E A L C Y C L E A N D T I M E A C C O U N T I N G On 4 MPI ranks, each using 8 OpenMP threads Computing: Num Num CallWall time Giga-Cycles Ranks Threads Count (s) total sum% - Domain decomp. 48 151592.099 137554.334 2.2 DD comm. load 48751 0.057 4.947 0.0 Neighbor search48 150001 665.072 57460.919 0.9 Launch GPU ops.48 1502 967.023 83548.916 1.3 Comm. coord. 487352488.263 214981.185 3.5 Force 487517037.401 608018.042 9.8 Wait + Comm. F 487513931.222 339650.132 5.5 * PME mesh 48 751 40799.9373525036.971 56.7* Wait GPU nonlocal 487511985.151 171513.300 2.8 Wait GPU local 48751 68.365 5906.612 0.1 NB X/F buffer ops. 48 29721229.406 106218.328 1.7 Write traj.48830 28.245 2440.304 0.0 Update 487512479.611 214233.669 3.4 Constraints487517041.030 608331.635 9.8 Comm. energies 48 150001 14.250 1231.154 0.0 Rest1601.588 138374.139 2.2 - Total 71928.719 6214504.588 100.0 - Breakdown of PME mesh computation - PME redist. X/F48 15028362.454 722500.151 11.6 PME spread/gather 48 1502 14836.350 1281832.463 20.6 PME 3D-FFT 48 15028985.776 776353.949 12.5 PME 3D-FFT Comm. 48 15027547.935 652127.220 10.5 PME solve Elec 487511025.249 88579.550 1.4 - First, I would like to know whether this is a big problem and second, I want to know how to improve my performance? Does it mean that my GPU is running too fast and CPU is waiting. BTW, what does the wait GPU nonlocal refer to? Thank you. Yunlong -- Yunlong Liu, PhD Candidate Computational Biology and Biophysics Department of Biophysics and Biophysical Chemistry School of Medicine, The Johns Hopkins University Email: yliu...@jhmi.edu Address: 725 N Wolfe St, WBSB RM 601, 21205 -- Gromacs Users mailing list * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/GMX-Users_List before posting! * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists * For (un)subscribe requests visit https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or send a mail to gmx-users-requ...@gromacs.org.
Re: [gmx-users] regarding MSD
Please reply. Reposting the same query again: I have read few papers that determine transition temperature from the plot of average MSD of hydrogen atoms of protein versus temperature. My question is: At a particular temperature, we get a linear curve for MSD versus time, is it reasonable to calculate average MSD over all such time points? Is this the average that is plotted in papers (or something is missing) ? My doubt is won't this average depend on the number of time points (due to its linear nature)? Actually I am trying to reproduce the results of some published data. Although I am getting the same transition temperature but the MSD values are coming different (eg at a particular temperature if I average all the MSD values, I am getting value of 15000 while reported value is 1.5 - both values in same unit angstrom square) On Fri, Aug 22, 2014 at 7:15 PM, Nidhi Katyal nidhikatyal1...@gmail.com wrote: -- Forwarded message -- From: Nidhi Katyal nidhikatyal1...@gmail.com Date: Fri, Aug 22, 2014 at 11:41 AM Subject: Re: regarding MSD To: Discussion list for GROMACS users gmx-us...@gromacs.org Hello I have posted the query earlier but havent got any reply and so reposting it again. I have read few papers that determine transition temperature from the plot of average MSD of hydrogen atoms of protein versus temperature. My question is: At a particular temperature, we get a linear curve for MSD versus time, is it reasonable to calculate average MSD over all such time points? Is this the average that is plotted in papers (or something is missing) ? My doubt is won't this average depend on the number of time points (due to its linear nature)? Actually I am trying to reproduce the results of some published data. Although I am getting the same transition temperature but the MSD values are coming different (eg at a particular temperature if I average all the MSD values, I am getting value of 15000 while reported value is 1.5 - both values in same unit angstrom square) Any help is highly appreciated. On Thu, Aug 21, 2014 at 9:56 PM, Nidhi Katyal nidhikatyal1...@gmail.com wrote: Hello all I have read few papers that determine transition temperature from the plot of average MSD versus temperature. My question is: At a particular temperature, we get a linear curve for MSD versus time, is it reasonable to calculate average MSD over all such time points? Is this the average that is plotted in papers (or something is missing) ? My doubt is won't this average depend on the number of time points (due to its linear nature)? Any help is highly appreciated. Thanks Nidhi -- Gromacs Users mailing list * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/GMX-Users_List before posting! * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists * For (un)subscribe requests visit https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or send a mail to gmx-users-requ...@gromacs.org.
[gmx-users] interpreting g_hydorder results
One of my friends have posted the same query earlier but hasn't got any reply. Now, I am also having the same doubt and so posting the question on behalf of both of us: We would like to calculate both distance and angle water orientational order. We have made an index file containing all oxygen atoms of water and used trjorder as: g_hydorder -f *.xtc -s *.tpr -n *.ndx -o file1_1 file2_1 -or file1_2 file2_2 How to interpret the results of the output files? Both output files file1_2 and file2_2 contain the same content. Won't one should contain distance and other angle orientational order parameter values? Also We expect parameter values to be less than or equal to 1. But the values in the file looks something like the following (all greater than 1): #Legend #TBlock #Xbin Ybin Z t 0 0 0 6.5 0 1 6.5 0 2 4.5 0 3 3.5 0 4 6.5 0 5 4.5 0 6 5.5 1 0 6.5 1 1 4.5 1 2 5.5 1 3 3.5 1 4 5.5 1 5 4.5 1 6 5.5 2 0 4.5 . . Please help us in interpreting this file. Looking forward to reply this time Any help is highly appreciated. -- Gromacs Users mailing list * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/GMX-Users_List before posting! * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists * For (un)subscribe requests visit https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or send a mail to gmx-users-requ...@gromacs.org.
