[gmx-users] LINCS warning

Justin A. Lemkul jalemkul at vt.edu
Thu Aug 14 17:58:32 CEST 2008



serdar durdagi wrote:
> Dear all,
>  
> I am making "drg+lipid" simulations with gmx. From the 9 series of 
> experiments all of them worked fine for 250 ps equilubration run. 
> However, when I start the real simulation, 4 of them stopped after 300 
> ps (I have setted the simualtion time to 2.5 ns). It complains the LINCS 
> warning. "relative constraint deviation after LINC".
>  
> All the systems are very similar, just different conformations of drug. 
> So, I can not see any reason why some of them are working fine and some 
> of them not.
>  

Those different conformations may have different (bad) interactions with the 
other elements of your system.  Having described nothing about your preparation, 
minimization, or equilibration scheme, that's about the best I can see to offer.

View the trajectory and see where things are starting to explode.  That will 
give you a hint as to where the problem lies.  There are hundreds of posts about 
LINCS warnings in the mailing list archive, as well as the following wiki site:

http://wiki.gromacs.org/index.php/blowing_up

These sources should provide you with many things to try.

One final note: Depending on the size of these drug molecules, it may not be 
appropriate to couple them to their own temperature bath.  Insufficient degrees 
of freedom (i.e., coupling a few ions to their own bath) can lead to the same 
type of weird, random explosions.  For more information, again, consult the wiki:

http://wiki.gromacs.org/index.php/Thermostats

-Justin

> I attached the last steps of log file and used mdp file.
>  
> Thank you very much in advance for solution suggestions.
>  
>  
> Serdar Durdagi
>  
>  
> title = CB1_conf_a MD
> cpp = /usr/bin/cpp
> constraints = all-bonds
> integrator = md
> dt = 0.002 ; ps !
> nsteps = 1250000
> nstcomm = 1
> nstxout = 500
> nstvout = 0
> nstfout = 0
> nstlog = 500
> nstlist = 10
> ns_type = grid
> rlist = 1.0
> coulombtype = PME
> rcoulomb = 1.0
> vdwtype = cut-off
> rvdw = 1.4
> fourierspacing = 0.12
> fourier_nx = 0
> fourier_ny = 0
> fourier_nz = 0
> pme_order = 4
> ewald_rtol = 1e-5
> optimize_fft = yes
> ; Berendsen temperature coupling is on
> Tcoupl = berendsen
> tau_t = 0.1 0.1 0.1
> tc-grps = DPP C6 SOL
> ref_t = 300 300 300
> ; Pressure coupling is on
> Pcoupl = no
> tau_p = 0.5
> compressibility = 4.5e-5
> ref_p = 1.0
> Generate velocities is on at 300 K.
> gen_vel = yes
> gen_temp = 300.0
> gen_seed = 173529
>  
>  
>  
>  
>            Step           Time         Lambda
>          166500      333.00000        0.00000
>    Rel. Constraint Deviation:  Max    between atoms     RMS
>        Before LINCS         0.006301   4163   4164   0.001222
>         After LINCS         0.000144     27     28   0.000006
>    Energies (kJ/mol)
>           Angle    Proper Dih. Ryckaert-Bell.  Improper Dih.          LJ-14
>     1.08817e+04    2.92391e+03    5.33679e+03    3.48481e+02    1.18752e+03
>      Coulomb-14        LJ (SR)        LJ (LR)   Coulomb (SR)   Coul. recip.
>     1.33953e+04   -6.78212e+03   -2.28400e+03   -1.91715e+05   -1.13117e+05
>       Potential    Kinetic En.   Total Energy    Temperature Pressure (bar)
>    -2.79825e+05    4.07337e+04   -2.39091e+05    3.03482e+02   -3.62649e+02
>            Step           Time         Lambda
>          167000      334.00000        0.00000
>    Rel. Constraint Deviation:  Max    between atoms     RMS
>        Before LINCS         0.006221   2094   2095   0.001243
>         After LINCS         0.000050     27     28   0.000004
>    Energies (kJ/mol)
>           Angle    Proper Dih. Ryckaert-Bell.  Improper Dih.          LJ-14
>     1.11706e+04    2.98252e+03    5.26699e+03    3.75113e+02    1.34753e+03
>      Coulomb-14        LJ (SR)        LJ (LR)   Coulomb (SR)   Coul. recip.
>     1.30631e+04   -7.42424e+03   -2.27672e+03   -1.89582e+05   -1.12967e+05
>       Potential    Kinetic En.   Total Energy    Temperature Pressure (bar)
>    -2.78044e+05    3.95852e+04   -2.38459e+05    2.94925e+02   -2.05298e+02
>            Step           Time         Lambda
>          167500      335.00000        0.00000
>    Rel. Constraint Deviation:  Max    between atoms     RMS
>        Before LINCS         0.005474    693    694   0.001211
>         After LINCS         0.000078     27     28   0.000004
>    Energies (kJ/mol)
>           Angle    Proper Dih. Ryckaert-Bell.  Improper Dih.          LJ-14
>     1.10570e+04    2.92074e+03    5.41756e+03    3.52792e+02    1.27318e+03
>      Coulomb-14        LJ (SR)        LJ (LR)   Coulomb (SR)   Coul. recip.
>     1.29374e+04   -7.77397e+03   -2.27790e+03   -1.89057e+05   -1.13016e+05
>       Potential    Kinetic En.   Total Energy    Temperature Pressure (bar)
>    -2.78166e+05    4.01726e+04   -2.37993e+05    2.99302e+02   -2.13536e+02
> 
> Step 167969, time 335.938 (ps)  LINCS WARNING
> relative constraint deviation after LINCS:
> max inf (between atoms 3 and 4) rms inf
> bonds that rotated more than 30 degrees:
>  atom 1 atom 2  angle  previous, current, constraint length
>       2      3   31.7    0.1530   0.1802      0.1530
>       3      4   71.9    0.1530 
> 2265021108479420332760918618026182082596758987575428182455396865361974544095646526528815104.0000      
> 0.1530
>       4      5   84.9    0.1530 
> 18122984199645729100337329541298157025024538645594811987064424745522897956771954290799411200.0000      
> 0.1530
>       5      6   86.3    0.1530 
> 119175309066877201840333474141339178556441000114517345446131726568065607288857704216068620288.0000      
> 0.1530
>       6      7   83.2    0.1530 
> 319516206321530845988576783668094567874060447793487769269077323346592450103529992297220407296.0000      
> 0.1530
>       7      8   90.1    0.1852 
> 1215659572675149285233162397268999839681310750651580520597516723093456091315807918022002212864.0000      
> 0.1852
>       7     11   90.0    0.3827 
> 261046278995437240163010555897466446819104052294790175823713013006178876940639100930185232384.0000      
> 0.3827
>       7     12   85.9    2.1222 
> 708122676010602206123407194621458163923965667621590605923744064304768598320784768943452585984.0000      
> 2.1222
>       8      9   89.7    0.1830 
> 1464090871981283196025364104977632977506718699519384307354293090385664459392658757834091003904.0000      
> 0.1830
>       9     10   89.4    0.1530 
> 1642496700465256611058147631762101542391865462505379007077289495407248437142902530819236036608.0000      
> 0.1530
>      10     11   90.1    0.1830 
> 756767949452499811070392082343079516984060143555343448612396645526001354011557126580748681216.0000      
> 0.1830
>      12     13   93.3    0.1390 
> 1675013654744810844287719234237265294947410972536560437889789182123995586451476744156309618688.0000      
> 0.1390
>      12     14   85.1    0.1390 
> 329283409277106964914359855618901648092274440312854462821854172823229415900192821585052172288.0000      
> 0.1390
>      13     28   92.0    0.1390 
> 704336240987254356289474657410431622881423034652003910924693084338836951238889120976668196864.0000      
> 0.1390
>      14     15   99.1    0.1390 
> 379860931583656159501355512782081590450061932169874874128503353575000723021905332351770034176.0000      
> 0.1390
>      15     16   90.1    1.4429 
> 206242205098337185268222500120712681530171088335436475613630821288724906666004435554722119680.0000      
> 1.4429
>      15     27   91.8    0.1390 
> 398684384369289490166841022015490990129049715188945258148097433284725455687338625841045176320.0000      
> 0.1390
>      16     17  124.5    0.1435 
> 5471440768467994537804435788744902781374726537963888385752468854524825194082290680987648000.0000      
> 0.1435
>      17     18   78.2    0.1530 
> 1217841628171641512793797538386485535450621055372659463190106114383330186479756409921601536.0000      
> 0.1530
>      17     19   80.7    0.1530 
> 1217841628171641512793797538386485535450621055372659463190106114383330186479756409921601536.0000      
> 0.1530
>      17     20  113.4    0.1530 
> 4056018304815038460726471748512358923224231361828694303945468971580026881584083840777846784.0000      
> 0.1530
>      20     21  104.5    0.1530 
> 5069114535236862410529809697539370521064020867182026484700468134800923155949405760991002624.00
>  
>  
>  
> 
> 
> __________________________________________________
> Do You Yahoo!?
> Sie sind Spam leid? Yahoo! Mail verfügt über einen herausragenden Schutz 
> gegen Massenmails.
> http://mail.yahoo.com
> 
> 
> ------------------------------------------------------------------------
> 
> _______________________________________________
> gmx-users mailing list    gmx-users at 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-request at gromacs.org.
> Can't post? Read http://www.gromacs.org/mailing_lists/users.php

-- 
========================================

Justin A. Lemkul
Graduate Research Assistant
Department of Biochemistry
Virginia Tech
Blacksburg, VA
jalemkul[at]vt.edu | (540) 231-9080
http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin

========================================



More information about the gromacs.org_gmx-users mailing list