[gmx-users] gromacs.org_gmx-users Digest, Vol 144, Issue 119

bharat gupta bharat.85.monu at gmail.com
Fri Apr 22 09:07:08 CEST 2016


On Thu, Apr 21, 2016 at 7:12 PM, Groenhof, Gerrit <ggroenh at gwdg.de> wrote:

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> Hi,
>
> Indeed, Link atoms have to be added to the .gro file. The atom indexing in
> the .gro file is not used, so no need to renumber. A simple editconf can do
> that for you if too, if you would like to have the numbering correct.
> However, you need to adjust the total number of atoms at the top of the
> .gro file.
>
> for the bonded interactions, you should remove the gb_x , because these
> defines contain the bond type information as well. Easiest is to add a ';'
> like this
>
> 1851  1853     2   ; gb_10
>
> which means that what comes after is ignored.
>
> good luck,
>
> Gerrit
>

Hi Gerrit,

Thank you for your previous response to my queries.

I made the changes according to your suggestion and I got the following
error while running the grompp command:
$ gmx grompp -f qmmm1.mdp -c start.gro -n QM_MM.ndx -p topol.top -o
qmmm1.tpr

WARNING 1 [file qmmm1.mdp, line 62]:
  Unknown left-hand 'continuation' in parameter file


Setting the LD random seed to 1943711519
Generated 189 of the 2080 non-bonded parameter combinations

-------------------------------------------------------
Program gmx grompp, VERSION 5.1.2
Source code file:
/home/Bharat/Documents/gromacs-5.1.2/src/gromacs/gmxpreprocess/toppush.c,
line: 1806

Fatal error:
[ file topol.top, line 22177 ]:
Atom index (3563) in virtual_sites2 out of bounds (1-3496).
This probably means that you have inserted topology section "virtual_sites2"
in a part belonging to a different molecule than you intended to.
In that case move the "virtual_sites2" section to the right molecule.
For more information and tips for troubleshooting, please check the GROMACS
website at http://www.gromacs.org/Documentation/Errors

I have included the LA atoms in the topology file under the section name
[dummies2]. Here's my qmmm1.mdp file:

title       = Protein-ligand complex NVT equilibration
define      = -DPOSRES  ; position restrain the protein and ligand
; Run parameters
integrator  = md        ; leap-frog integrator
nsteps      = 500000     ; 2 * 50000 = 100 ps
dt          = 0.002     ; 2 fs
; Output control
nstxout     = 500       ; save coordinates every 1.0 ps
nstvout     = 500       ; save velocities every 1.0 ps
nstenergy   = 500       ; save energies every 1.0 ps
nstlog      = 500       ; update log file every 1.0 ps
energygrps  = Protein 5YWR
; Bond parameters
continuation    = no            ; first dynamics run
constraint_algorithm = lincs    ; holonomic constraints
constraints     = all-bonds     ; all bonds (even heavy atom-H bonds)
constrained
lincs_iter      = 1             ; accuracy of LINCS
lincs_order     = 4             ; also related to accuracy
unconstrained_start      = no
Shake-SOR                = no
shake_tol                = 0.0001
lincs_warnangle          = 30
morse                    = no
; Neighborsearching
cutoff-scheme   = Verlet
ns_type         = grid      ; search neighboring grid cells
nstlist         = 10        ; 20 fs, largely irrelevant with Verlet
rcoulomb        = 1.4       ; short-range electrostatic cutoff (in nm)
rvdw            = 1.4       ; short-range van der Waals cutoff (in nm)
; Electrostatics
coulombtype     = PME       ; Particle Mesh Ewald for long-range
electrostatics
pme_order       = 4         ; cubic interpolation
fourierspacing  = 0.16      ; grid spacing for FFT
; Temperature coupling
tcoupl      = V-rescale                     ; modified Berendsen thermostat
tc-grps     = Protein_5YWR Water_and_ions    ; two coupling groups - more
accurate
tau_t       = 0.1   0.1                     ; time constant, in ps
ref_t       = 300   300                     ; reference temperature, one
for each group, in K
; Pressure coupling
pcoupl      = no        ; no pressure coupling in NVT
; Periodic boundary conditions
pbc         = xyz       ; 3-D PBC
; Dispersion correction
DispCorr    = EnerPres  ; account for cut-off vdW scheme
; Velocity generation
gen_vel                  = no
gen_temp                 = 00
gen_seed                 = 18111976


QMMM                     = yes
QMMM-grps                = Protein_AS_5YWR
QMmethod                 = am1
QMMMscheme               = normal
QMbasis                  = sto-3g
QMcharge                 = 0
QMmult                   = 1



the QM parameters were copied from a tutorial (
http://www.dddc.ac.cn/embo04/practicals/qmmm/qmmmvacuum.html) to test the
trial run. I am using ORCA for QMMM calculations. Could you please let me
know how to rectify these errors.



Regards
BM



>
> Message: 3
> Date: Thu, 21 Apr 2016 17:43:47 +0900
> From: bharat gupta <bharat.85.monu at gmail.com>
> To: Discussion list for GROMACS users <gmx-users at gromacs.org>
> Subject: Re: [gmx-users] Defining LA atoms in .gro file
> Message-ID:
>         <CAAh+zSV7BrctXYs0=
> yoAekVnFbxeES+c0zTxODqA8jGin10ysQ at mail.gmail.com>
> Content-Type: text/plain; charset=UTF-8
>
> Dear GMX Users,
>
> I am trying to perform QM/MM simulation for my system and I need to define
> LA for the boundary between QM and MM region. I have the boundary regions
> but I don't know how to add them in the gro file. Do I have to manually
> modify the .gro file, if that's the case, adding, them manually how do I
> renumber the rest of the atoms and residues? Here's what I have done:
>
>  3715YWR   H21 3562   4.283   4.647   4.755 -1.1354  1.0843 -0.8713
>   372XXX     LA 3563   2.475   3.856   2.040 -0.0020 -0.1066  0.1995
>   373XXX     LA 3564   0.475   3.856   2.040 -0.0020 -0.1066  0.1995
>   374XXX     LA 3565   1.475   3.856   2.040 -0.0020 -0.1066  0.1995
>   375XXX     LA 3566   3.475   3.856   2.040 -0.0020 -0.1066  0.1995
>   376XXX     LA 3567   0.875   3.856   2.040 -0.0020 -0.1066  0.1995
>   377XXX     LA 3568   1.575   3.856   2.040 -0.0020 -0.1066  0.1995
>   372SOL     OW 3563   3.414   3.445   2.243 -0.1786 -0.5561  0.4692
>   372SOL    HW1 3564   3.479   3.440   2.167  0.5613 -1.1084  1.1215
>   372SOL    HW2 3565   3.329   3.488   2.212  0.4389  0.0440 -0.4374
>   373SOL     OW 3566   1.589   3.334   2.348  0.6300  0.1793 -0.1279
>   373SOL    HW1 3567   1.639   3.413   2.384  1.2205  0.0166 -0.5746
>   373SOL    HW2 3568   1.588   3.337   2.248 -1.5585  0.9770 -0.1508
>   374SOL     OW 3569   5.280   6.227   4.070  0.5862 -0.1571 -0.6930
>
> So, I added the LA atoms between atom no H21/3562 and OW/3563 manually.
> Please let me whether this is the correct way of adding the LA atoms ?
>
> Also, I need to modify the bond_types as well in the topology file to 5. Is
> this the correct way:
>
> 1851  1853     2    gb_10
>  1853  1854     5    gb_2
>  1853  1855     5    gb_21
>  1855  1856     5    gb_27
>  1855  1862     5    gb_27
>  1856  1857     5    gb_27
>  1857  1858     5    gb_27
>  1858  1859     5    gb_5
>  1858  1860     5    gb_13
>  1860  1861     5    gb_1
>  1862  1863     5    gb_5
>  1862  1864     2    gb_10
>  1864  1865     2    gb_2
>
> I haven't changed the values for C0 for the QM atoms but I have changed
> their type to 5.
>
> --
> *Best Regards*
> BM
>
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