[gmx-users] Re: gmx-users] Simple L-J Particles' simulation

David spoel at xray.bmc.uu.se
Wed Sep 24 18:29:01 CEST 2003


On Wed, 2003-09-24 at 18:04, Albert Sun wrote:
> Dear Groeten, David and Gmx-users,
> I have a few stupid questions:
> How to simulate simple Lennard Jones particles in Gromacs? 
> In .top file, we don't need input bond and angle data, is it right?
> How to specify force field in .top file

here's an example from the gmx testset.

>  
> Greatly appreciate your clarification.
>  
> Thanks 
>  
> Albert
> Albert Sun <albert_sun9 at yahoo.com> wrote: 
>         Dear David and Gmx-users,
>         I have a few stupid questions:
>         How to simulate simple Lennard Jones particles in Gromacs? 
>         In .top file, we don't need input bond and angle data, is it
>         right?
>         How to specify force field in .top file?
>          
>         Greatly appreciate your clarification.
>          
>         Thanks 
>          
>         Albert
>         Albert Sun <albert_sun9 at yahoo.com> wrote:
>                 Dear Groeten, David
>                 How to start simple Lennard Jones particles in
>                 Gromacs?
>                 by specify force field: ffgmx
>                 thanks!
>                  
>                 Albert
>                  
>                 David <spoel at xray.bmc.uu.se> wrote:
>                         On Sat, 2003-09-20 at 21:09, Albert Sun wrote:
>                         > Hi, Dear Anton,
>                         > Atoms exploded problem still remains, when I
>                         view .trr file by VMD,
>                         > all atoms suddenly disappear.
>                         > I tried ngmx, it had error: float exception.
>                         > I tried trjconv -dump, it showed warning:
>                         "no output, trajectory ended
>                         > at 3" 
>                         > 
>                         > could you give me more hints ? 
>                         
>                         
>                         It seems to me that you have just a weird
>                         system with all atoms placed
>                         in a plane, and large forces between them.
>                         
>                         If you intend to simulate some sort of two
>                         dimensional crystal, you
>                         should probably start with simple Lennard
>                         Jones particles.
>                         -- 
>                         Groeten, David.
>                         ________________________________________________________________________
>                         Dr. David van der Spoel, Dept. of Cell and
>                         Molecular Biology
>                         Husargatan 3, Box 596, 75124 Uppsala, Sweden
>                         phone: 46 18 471 4205 fax : 46 18 511 755
>                         spoel at xray.bmc.uu.se spoel at gromacs.org
>                         http://xray.bmc.uu.se/~spoel
>                         ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>                         
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-- 
David.
________________________________________________________________________
David van der Spoel, PhD, Assist. Prof., Molecular Biophysics group,
Dept. of Cell and Molecular Biology, Uppsala University.
Husargatan 3, Box 596,  	75124 Uppsala, Sweden
phone:	46 18 471 4205		fax: 46 18 511 755
spoel at xray.bmc.uu.se	spoel at gromacs.org   http://xray.bmc.uu.se/~spoel
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-------------- next part --------------
Argon
  125
    1Argon   AR    1   4.895   1.092   4.682 -1.1326  1.5028 -0.3139
    2Argon   AR    2   1.156   0.524   1.448  1.2795 -0.2792  0.8730
    3Argon   AR    3   0.985   2.029   2.012  1.7219 -0.7373 -1.1915
    4Argon   AR    4   4.924   0.489   3.687 -0.5243  2.0315 -0.3342
    5Argon   AR    5   0.464   1.205   3.037 -0.6154  0.8562 -0.4888
    6Argon   AR    6   1.330   2.145   0.086 -0.4231 -0.7396  0.5885
    7Argon   AR    7   0.460   1.527   1.252  0.2134  0.1881 -0.0428
    8Argon   AR    8   0.591   4.622   2.154 -0.1886  0.5678  0.9706
    9Argon   AR    9   1.235   0.835   3.569 -0.0540  0.7621  0.2812
   10Argon   AR   10   4.860   2.987   4.888  0.7087  0.8855 -0.0666
   11Argon   AR   11   1.808   3.150   0.377  1.0813 -0.0937 -0.2159
   12Argon   AR   12   0.943   2.452   0.967 -1.2118  0.9035  0.1153
   13Argon   AR   13   0.544   3.039   2.228 -0.4095  1.2861 -0.7635
   14Argon   AR   14   5.040   1.969   2.361 -2.3891 -0.7822 -0.2271
   15Argon   AR   15   3.960   4.501   0.337 -0.9374 -0.6907  1.0124
   16Argon   AR   16   1.172   3.746   0.959  0.1516 -0.1523  0.4900
   17Argon   AR   17   2.280   3.868   1.392  0.1532  0.2206  0.4628
   18Argon   AR   18   1.233   3.746   2.096  1.6713  0.7138  1.8370
   19Argon   AR   19   5.024   2.452   3.417  0.2566 -0.2714 -0.0202
   20Argon   AR   20   0.175   3.430   3.782 -0.1056  1.4345  0.2331
   21Argon   AR   21   2.726   1.305   0.712 -0.0390 -1.5948 -0.5293
   22Argon   AR   22   0.207   3.874   1.631 -2.4302 -0.0397  1.9954
   23Argon   AR   23   0.285   4.788   3.105  0.2782  0.9295  0.2530
   24Argon   AR   24   1.176   2.816   4.145 -0.1406  0.4559 -1.2429
   25Argon   AR   25   4.318   4.740   4.495  0.5516  0.4663  2.1848
   26Argon   AR   26   1.864   4.798   4.629  1.5901 -1.5084  0.3228
   27Argon   AR   27   0.344   0.831   0.485 -0.3221  1.4094  1.0212
   28Argon   AR   28   2.268   0.316   3.079 -0.7959  1.1356  1.9309
   29Argon   AR   29   2.107   4.413   2.785 -0.7391 -0.3921  0.0283
   30Argon   AR   30   0.965   0.165   4.325  0.0312  0.3614  0.0970
   31Argon   AR   31   2.238   1.695   4.984  0.2919 -0.8347 -0.7021
   32Argon   AR   32   1.341   1.176   0.676  0.8544  0.2996 -0.6172
   33Argon   AR   33   0.908   2.289   3.208  0.5111  0.0979  1.3060
   34Argon   AR   34   1.847   0.781   4.379  1.4208  0.4866  0.5295
   35Argon   AR   35   0.366   2.406   4.456 -0.1472  0.4125  1.2066
   36Argon   AR   36   2.901   2.956   1.493  1.2892 -0.6305  1.0128
   37Argon   AR   37   5.058   2.524   1.464  0.0022 -1.7319 -0.4964
   38Argon   AR   38   2.803   2.480   3.679 -0.0907  1.2107 -1.8332
   39Argon   AR   39   1.886   2.325   3.241  0.6276 -1.8375 -0.8451
   40Argon   AR   40   0.836   3.294   4.991  0.6273  0.7660 -1.3883
   41Argon   AR   41   2.035   4.724   0.719  0.3153  0.4792  2.2771
   42Argon   AR   42   2.171   3.352   2.458  0.5924 -0.7270 -0.6602
   43Argon   AR   43   1.658   3.025   1.570  1.8708  0.4716 -0.1615
   44Argon   AR   44   2.015   3.318   3.592 -1.1776 -2.0891 -1.6319
   45Argon   AR   45   1.019   4.226   0.114 -1.4335 -0.0953 -0.5499
   46Argon   AR   46   1.621   4.722   1.731  0.3118  0.2862  0.9394
   47Argon   AR   47   1.236   0.209   2.570 -0.3800  0.3034 -0.2262
   48Argon   AR   48   1.107   3.405   3.175  0.7078  0.6353 -0.2058
   49Argon   AR   49   1.036   3.980   4.023 -0.7442  0.3863  0.5171
   50Argon   AR   50   4.942   3.959   0.028 -0.4945 -0.5427 -0.3578
   51Argon   AR   51   2.750   2.001   1.596  0.2617  0.0781 -1.1608
   52Argon   AR   52   1.769   1.280   1.829  1.0091 -0.0491 -1.7755
   53Argon   AR   53   3.892   0.147   2.244  0.0665  0.3800 -0.2316
   54Argon   AR   54   1.322   4.776   3.451 -0.7496 -0.7912  1.4578
   55Argon   AR   55   0.376   1.468   3.935 -0.6509 -1.8500 -0.8614
   56Argon   AR   56   2.728   2.508   0.449  0.9513  1.5416 -0.5461
   57Argon   AR   57   1.976   1.948   0.960  0.5224 -0.5848 -0.3202
   58Argon   AR   58   1.479   1.402   2.795  0.0270  1.0455  0.6138
   59Argon   AR   59   2.326   4.300   3.837 -0.5198  1.0516 -0.3477
   60Argon   AR   60   1.583   1.807   4.061  0.5585 -0.0307 -1.4619
   61Argon   AR   61   3.630   2.633   0.831 -2.7969  0.6538 -1.5914
   62Argon   AR   62   2.044   2.243   2.243 -0.4373 -2.1214  2.6278
   63Argon   AR   63   4.021   3.213   3.358 -0.0751  1.9466 -1.6609
   64Argon   AR   64   2.475   1.342   3.562 -0.0774 -1.2108  0.4061
   65Argon   AR   65   2.641   3.753   0.327 -0.3352  1.0297  0.1584
   66Argon   AR   66   2.921   4.776   4.908 -0.7096  0.6935 -0.4993
   67Argon   AR   67   3.117   4.647   0.831  0.3148  0.2864 -0.8219
   68Argon   AR   68   3.055   3.628   3.135  1.7630  2.2576  0.7552
   69Argon   AR   69   3.159   2.021   4.795  0.7280  1.8829  0.3458
   70Argon   AR   70   2.079   2.608   4.588 -0.9824  0.5748  1.0455
   71Argon   AR   71   3.146   0.714   1.366  0.1684 -0.5257  1.2033
   72Argon   AR   72   3.148   3.803   1.998  0.4269 -1.2197 -0.2678
   73Argon   AR   73   3.051   4.715   2.822 -0.0300 -1.2029 -0.5454
   74Argon   AR   74   1.833   3.775   4.732 -1.2605 -0.6808  0.2866
   75Argon   AR   75   2.146   0.441   1.263  0.3308 -0.4730 -1.2353
   76Argon   AR   76   3.897   1.349   0.074  0.8640 -0.4883 -1.2810
   77Argon   AR   77   2.568   0.909   2.276 -1.3364 -0.5167  0.5504
   78Argon   AR   78   0.750   4.609   1.037  1.6011 -0.0479  0.4901
   79Argon   AR   79   3.895   5.063   3.489 -0.3064 -0.0822  1.2432
   80Argon   AR   80   0.960   1.168   4.821  1.1169 -1.3025  0.0374
   81Argon   AR   81   4.374   2.044   4.610  0.5650 -0.3312 -0.1887
   82Argon   AR   82   2.845   1.989   2.744  1.0250 -0.9478 -0.2386
   83Argon   AR   83   3.488   1.355   2.174 -0.7045  0.7480 -0.7522
   84Argon   AR   84   3.232   0.861   3.156  1.1879 -0.9798 -0.4548
   85Argon   AR   85   2.864   1.026   4.414 -1.0152  0.4205 -1.3106
   86Argon   AR   86   4.426   3.428   0.770 -0.8505  1.5544  0.3785
   87Argon   AR   87   3.404   2.895   2.547 -0.4559  0.2936 -0.2803
   88Argon   AR   88   4.603   1.115   2.034  0.6018  1.7600 -0.7041
   89Argon   AR   89   3.557   1.675   3.847 -0.6226 -1.2764  0.5321
   90Argon   AR   90   3.600   3.419   0.075  0.6881  0.2689  0.9736
   91Argon   AR   91   3.401   3.726   0.994 -0.6749 -0.7556  0.0629
   92Argon   AR   92   0.192   5.090   5.003 -0.0606 -1.0682  0.0510
   93Argon   AR   93   4.005   3.979   2.602 -0.6517 -1.4648  0.7342
   94Argon   AR   94   2.751   3.291   4.345  0.5387  0.1697  0.2571
   95Argon   AR   95   4.751   4.548   0.992 -1.5935  0.0305 -1.0997
   96Argon   AR   96   4.057   3.097   1.700 -0.1356 -0.5532  1.4938
   97Argon   AR   97   2.915   4.913   1.863 -0.6477 -0.2058  1.1749
   98Argon   AR   98   0.051   0.314   1.455  1.1463 -0.2553 -0.8920
   99Argon   AR   99   3.297   4.171   3.920  1.1921 -0.5417 -0.1280
  100Argon   AR  100   2.201   0.559   0.145 -2.1546  0.9850 -0.8281
  101Argon   AR  101   0.404   1.902   0.234  0.2684  1.4864  0.2678
  102Argon   AR  102   4.559   1.295   0.795 -0.8185  0.1854  3.4100
  103Argon   AR  103   4.678   4.559   2.114 -0.2692  0.4273  0.7147
  104Argon   AR  104   4.473   4.143   3.553  1.5132  0.6999  0.9178
  105Argon   AR  105   2.652   0.131   3.984  0.5066 -0.9274  0.2481
  106Argon   AR  106   4.582   2.308   0.634 -1.1833 -0.7555  0.5142
  107Argon   AR  107   3.620   1.557   1.056 -1.7076 -0.3213 -0.1657
  108Argon   AR  108   4.164   0.485   1.211 -0.6023  1.7699 -0.3569
  109Argon   AR  109   5.026   0.385   2.563  0.8574 -0.1411 -0.3869
  110Argon   AR  110   3.964   0.708   4.178  2.3516 -0.4632 -1.6643
  111Argon   AR  111   0.277   3.188   0.772 -1.5788 -1.8541 -1.1427
  112Argon   AR  112   4.168   2.084   1.670  0.4183 -0.6446 -1.1332
  113Argon   AR  113   0.614   1.006   2.078  0.3018  0.6311 -1.0163
  114Argon   AR  114   4.244   0.910   3.035  1.3939 -0.9413 -1.2160
  115Argon   AR  115   4.535   1.571   3.764 -0.2376 -1.2259 -1.2002
  116Argon   AR  116   4.307   0.407   0.122 -0.2502  1.7650 -0.2933
  117Argon   AR  117   1.214   0.252   0.313 -2.0761 -0.1607  0.1805
  118Argon   AR  118   4.591   2.945   2.467 -1.4596 -1.4980  0.5959
  119Argon   AR  119   4.101   2.120   2.835  2.4606  0.9035  0.7012
  120Argon   AR  120   3.740   2.689   4.154 -0.1941 -0.6392  0.4762
  121Argon   AR  121   3.318   0.461   0.368  0.7086  0.9908 -1.8400
  122Argon   AR  122   3.886   4.465   1.572  0.6610 -1.2269 -0.7330
  123Argon   AR  123   0.023   3.795   2.729  0.3992 -2.3672  0.3457
  124Argon   AR  124   4.287   3.674   4.386  0.4761 -0.8819 -0.9774
  125Argon   AR  125   0.185   4.445   4.270 -1.9450  0.9183  0.9863
   5.10000   5.10000   5.10000
-------------- next part --------------
; Argon

[ defaults ]
; nb-function	combinationrule
1		2

[ atomtypes ]
; type 	mass 	charge	ptype 	sig	eps
AR      1.0     0.0     A	1.0     1.0     

[ moleculetype ]
; molname      nrexcl
Argon          1

[ atoms ]
; id    at type res nr  residu name     at name cg nr
1       AR      1       Argon           AR      1 

[ system ]
; systemname
Argon

[ molecules ]
; molecule 	number
Argon		125
;Argon		2

-------------- next part --------------
;
;	File 'mdout.mdp' was generated
;	By user: spoel (500)
;	On host: h140n2fls34o1123.telia.com
;	At date: Thu May  8 10:57:52 2003
;

; VARIOUS PREPROCESSING OPTIONS
title                    = Yo
cpp                      = /lib/cpp
include                  = 
define                   = 

; RUN CONTROL PARAMETERS
integrator               = md
; start time and timestep in ps
tinit                    = 0.0
dt                       = 0.002
nsteps                   = 100
; after checkpoint or tpbconv restart we can start on step > 0
init_step                = 0
; mode for center of mass motion removal
comm-mode                = Linear
; number of steps for center of mass motion removal
nstcomm                  = 1
; group(s) for center of mass motion removal
comm-grps                = 

; LANGEVIN DYNAMICS OPTIONS
; Temperature, friction coefficient (amu/ps) and random seed
bd-temp                  = 300
bd-fric                  = 0
ld_seed                  = 1993

; ENERGY MINIMIZATION OPTIONS
; Force tolerance and initial step-size
emtol                    = 0.001
emstep                   = 0.1
; Max number of iterations in relax_shells
niter                    = 100
; Step size (1/ps^2) for minimization of flexible constraints
fcstep                   = 0
; Frequency of steepest descents steps when doing CG
nstcgsteep               = 1000

; OUTPUT CONTROL OPTIONS
; Output frequency for coords (x), velocities (v) and forces (f)
nstxout                  = 0
nstvout                  = 0
nstfout                  = 0
; Checkpointing helps you continue after crashes
nstcheckpoint            = 1000
; Output frequency for energies to log file and energy file
nstlog                   = 0
nstenergy                = 1
; Output frequency and precision for xtc file
nstxtcout                = 0
xtc_precision            = 1000
; This selects the subset of atoms for the xtc file. You can
; select multiple groups. By default all atoms will be written.
xtc-grps                 = 
; Selection of energy groups
energygrps               = Argon

; NEIGHBORSEARCHING PARAMETERS
; nblist update frequency
nstlist                  = 1
; ns algorithm (simple or grid)
ns_type                  = simple
; Periodic boundary conditions: xyz or no
pbc                      = xyz
; nblist cut-off        
rlist                    = 2.5
domain-decomposition     = no

; OPTIONS FOR ELECTROSTATICS AND VDW
; Method for doing electrostatics
coulombtype              = Cut-off
rcoulomb-switch          = 0
rcoulomb                 = 2.5
; Dielectric constant (DC) for cut-off or DC of reaction field
epsilon_r                = 1
; Method for doing Van der Waals
vdw-type                 = Cut-off
; cut-off lengths       
rvdw-switch              = 0
rvdw                     = 2.5
; Apply long range dispersion corrections for Energy and Pressure
DispCorr                 = No
; Spacing for the PME/PPPM FFT grid
fourierspacing           = 0.12
; FFT grid size, when a value is 0 fourierspacing will be used
fourier_nx               = 10
fourier_ny               = 10
fourier_nz               = 10
; EWALD/PME/PPPM parameters
pme_order                = 4
ewald_rtol               = 1e-05
ewald_geometry           = 3d
epsilon_surface          = 0
optimize_fft             = no

; GENERALIZED BORN ELECTROSTATICS
; Algorithm for calculating Born radii
gb_algorithm             = Still
; Frequency of calculating the Born radii inside rlist
nstgbradii               = 1
; Cutoff for Born radii calculation; the contribution from atoms
; between rlist and rgbradii is updated every nstlist steps
rgbradii                 = 2
; Salt concentration in M for Generalized Born models
gb_saltconc              = 0

; IMPLICIT SOLVENT (for use with Generalized Born electrostatics)
implicit_solvent         = No

; OPTIONS FOR WEAK COUPLING ALGORITHMS
; Temperature coupling  
tcoupl                   = no
; Groups to couple separately
tc-grps                  = Argon
; Time constant (ps) and reference temperature (K)
tau_t                    = 0.1
ref_t                    = 120
; Pressure coupling     
Pcoupl                   = no
Pcoupltype               = Isotropic
; Time constant (ps), compressibility (1/bar) and reference P (bar)
tau_p                    = 1.0
compressibility          = 
ref_p                    = 1.0
; Random seed for Andersen thermostat
andersen_seed            = 815131

; SIMULATED ANNEALING  
; Type of annealing for each temperature group (no/single/periodic)
annealing                = no
; Number of time points to use for specifying annealing in each group
annealing_npoints        = 
; List of times at the annealing points for each group
annealing_time           = 
; Temp. at each annealing point, for each group.
annealing_temp           = 

; GENERATE VELOCITIES FOR STARTUP RUN
gen_vel                  = no
gen_temp                 = 120
gen_seed                 = 173529

; OPTIONS FOR BONDS    
constraints              = none
; Type of constraint algorithm
constraint_algorithm     = Lincs
; Do not constrain the start configuration
unconstrained_start      = no
; Use successive overrelaxation to reduce the number of shake iterations
Shake-SOR                = no
; Relative tolerance of shake
shake_tol                = 0.0001
; Highest order in the expansion of the constraint coupling matrix
lincs_order              = 4
; Number of iterations in the final step of LINCS. 1 is fine for
; normal simulations, but use 2 to conserve energy in NVE runs.
; For energy minimization with constraints it should be 4 to 8.
lincs-iter               = 1
; Lincs will write a warning to the stderr if in one step a bond
; rotates over more degrees than
lincs_warnangle          = 30
; Convert harmonic bonds to morse potentials
morse                    = no

; ENERGY GROUP EXCLUSIONS
; Pairs of energy groups for which all non-bonded interactions are excluded
energygrp_excl           = 

; NMR refinement stuff 
; Distance restraints type: No, Simple or Ensemble
disre                    = No
; Force weighting of pairs in one distance restraint: Conservative or Equal
disre_weighting          = Equal
; Use sqrt of the time averaged times the instantaneous violation
disre_mixed              = no
disre_fc                 = 1000
disre_tau                = 1.25
; Output frequency for pair distances to energy file
nstdisreout              = 100
; Orientation restraints: No or Yes
orire                    = no
; Orientation restraints force constant and tau for time averaging
orire-fc                 = 0
orire-tau                = 0
orire-fitgrp             = 
; Output frequency for trace(SD) to energy file
nstorireout              = 100
; Dihedral angle restraints: No, Simple or Ensemble
dihre                    = No
dihre-fc                 = 1000
dihre-tau                = 0
; Output frequency for dihedral values to energy file
nstdihreout              = 100

; Free energy control stuff
free_energy              = no
init_lambda              = 0
delta_lambda             = 0
sc-alpha                 = 0
sc-sigma                 = 0.3

; Non-equilibrium MD stuff
acc-grps                 = 
accelerate               = 
freezegrps               = 
freezedim                = 
cos-acceleration         = 0

; Electric fields      
; Format is number of terms (int) and for all terms an amplitude (real)
; and a phase angle (real)
E-x                      = 
E-xt                     = 
E-y                      = 
E-yt                     = 
E-z                      = 
E-zt                     = 

; User defined thingies
user1-grps               = 
user2-grps               = 
userint1                 = 0
userint2                 = 0
userint3                 = 0
userint4                 = 0
userreal1                = 0
userreal2                = 0
userreal3                = 0
userreal4                = 0


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