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<style>.hmmessage P{margin:0px;padding:0px}body.hmmessage{FONT-SIZE: 10pt;FONT-FAMILY:Tahoma}</style>Dear Axel,<br><br>> that just means you are not using your MPI library correctly.<br>> QE assumes that consecutive MPI task ids are on the same node.<br>> most MPI libraries decide this based on the host/machine file,<br>> you have to read your MPI documentation how to arrange it the<br>> way it should would. you've seen from my timings, that it should<br>> work quite well. i am using OpenMPI and that package has on top<br>> of using hosts in the hostfile order the option to explicitely<br>> follow a round-robin or a by-node scheme when assigning MPI tasks.<br><br>I'm using MPICH2. So before using it, I should type command ' mpdboot -n 5 -f mpd.mashines'.<br>Maybe MPICH2 is not arrange the MPI task IDs in the way that Q-E assumes. So I'll try OPENMPI.<br>By the way, what vision does you recommend me to install?<br><br>> whether or not a gamma point calculation is sufficient is not<br>> determined by what other people do, but by the physics of the<br>> problem. <br><br>I have realized that. Late time maybe I doesn't say it in a right way. I'm using gamma point calculation<br>is not all because other people do so, but also many scientific papers of high impact and high quality, <br>such as paper of American Physical Society and American Chemical Society said using 2X2X1 mesh of k points<br>result in no large difference in energy of geometry from the gamma point only calculation. It's accepted <br>by most of scientists do the similar job for many years. I think it's not necessary to validate it by my self<br>because of the weakness of our calculation condition.<br><br>>that reminds me, you still owe us an explanation about<br>> the difference between 'commercial' and 'academic' calculations.<br>> i am _very_ curious about this.<br><br>I don't have enough authority to illustrate the difference beteen the two. I only saying something from my<br>own brain. I think Q-E is more suitable for scientific research, because of its free and open-source. And <br>another very important thing is Q-E also accepted by many resarchers who used Q-E and doing excellent<br>calculation. Also many pieces of work published on high quality and high impact Journals, like Nature Materials,<br>Journal of the American Chemical Society et al... But for comercial software, it cost a lot of money and the<br>source code is not open for their copyright. So it's much more like a black box. We can't know any detail that<br>how the results comes out. Maybe it's more accurate, but we can't believe it until we see the source code.<br>But if we know the source code, their secret is out. As far as I know, commercial software is more suitable for <br>industry researcher such as China National Petroleum Corporation or China Petrochemical Corporation et al.<br>The industry resarchers is often unwilling to say whether the resarch work using commercial simulation software <br>is accurate or not. We only see the product of the industry, but can't see what's the role of the software<br>in the product exploitation. Over all, people especially the scientists maybe couldn't trust the commercial software <br>until the see the source. Most scientist can't bear the big uncertain factor that the software brings to their resarching.<br><br>> you cannot. as you should have already seen from the numbers<br>> i sent you. g-space parallelization doesn't scale across gigabit<br>> ethernet using TCP/IP networking. just run the job within one<br>> node and then you can run 5 jobs at the same time.<br><br>Do you think the Q-E can achieve ~80 atoms gamma point calculation in one computer with single quad-core CPU<br>and 8Gmemory in less than 1 month running? Maybe it's too unbelievable task. <br><br>I'll try OPENMPI later, thank you for helping.<br><br><br><font size="4"><span style="font-family: Lucida Handwriting,Cursive;">Vega Lew</span></font><br>PH.D Candidate in Chemical Engineering<br>State Key Laboratory of Materials-oriented Chemical Engineering<br>College of Chemistry and Chemical Engineering<br>Nanjing University of Technology, 210009, Nanjing, Jiangsu, China<br><br><br><br /><hr />Get news, entertainment and everything you care about at Live.com. <a href='http://www.live.com/getstarted.aspx ' target='_new'>Check it out!</a></body>
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