[gmx-users] grompp does not find atomtype
jalemkul at vt.edu
Wed Jul 2 13:52:17 CEST 2014
On 7/2/14, 4:40 AM, Dawid das wrote:
> I have managed to deal with this problem in following way:
> In topology file some bonding parameters were actually missing but some
> bonding parameters were not needed, e.g. U-B or dihedral parameters for
> atoms which are not connected, that is they belong to different parts of my
> new residue.
> I found parameters for the missing ones and hashed (;) them out. Is it what
> I can do? Like I say, theses bonding parameters that I hashed out were for
> atom types which are not connected directly.
> Then I performed minimization with steepest descent and in output file I
> 4655e+05 Fmax= 6.53501e+03, atom= 1003^MStep= 426, Dmax= 2.5e-06 nm,
> Epot= -4.54655e+05 Fmax= 9.45125e+03, atom= 1003^MStep= 427, Dmax= 1.2e-06
> nm, Epot= -4.54655e+05 Fmax= 1.25724e+04, atom= 1003^M
> Stepsize too small, or no change in energy.
> Converged to machine precision,
> but not to the requested precision Fmax < 1000
> Double precision normally gives you higher accuracy.
> You might need to increase your constraint accuracy, or turn
> off constraints alltogether (set constraints = none in mdp file)
> writing lowest energy coordinates.
> Steepest Descents converged to machine precision in 428 steps,
> but did not reach the requested Fmax < 1000.
> Potential Energy = -4.5465475e+05
> Maximum force = 1.7057922e+04 on atom 1003
> Norm of force = 1.1677969e+02
> But I continued with NVT MD simulation. This is my nvt-md.mdp file:
> title = NVT MD
> integrator = md
> constraints = all-bonds
> dt = 0.001
> nsteps = 20000
> nstenergy = 100
> nstlist = 10
> nstxout = 1000
> nstvout = 1000
> nstfout = 0
> nstlog = 100
> nstxtcout = 1000
> xtcprecision = 500
> ns_type = grid
> coulombtype = PME
> rlist = 1.0
> rcoulomb = 1.0
> rvdw = 1.0
These cutoffs are incorrect for using CHARMM force fields. See previous posts
on proper settings.
> tcoupl = nose-hoover
> tc-grps = Protein SOL NA
> tau_t = 0.1 0.1 0.1 ;(3 numbers -> because 3 tc-grps)
> ref_t = 100 100 100 ;(3 numbers -> because 3 tc-grps)
Coupling water and ions separately is not sensible.
> Pcoupl = No
> gen_vel = yes
> gen_temp = 100
> gen_seed = 173529
> energygrps = Protein SOL NA
> constraint_algorithm = LINCS
> pbc = xyz
> And in my NVT output I got error for LINCS:
> relative constraint deviation after LINCS:
> rms 0.036755, max 1.509884 (between atoms 998 and 1000)
> bonds that rotated more than 30 degrees:
> atom 1 atom 2 angle previous, current, constraint length
> 1001 1003 62.1 0.1410 0.2032 0.1410
> 1001 1002 68.1 0.1240 0.1962 0.1240
> 1000 1001 88.1 0.1460 0.3276 0.1460
> 998 1000 90.0 0.1390 0.3489 0.1390
> 986 1000 90.7 0.1400 0.2237 0.1400
> 985 986 30.7 0.1300 0.1499 0.1300
> Wrote pdb files with previous and current coordinates
> These atoms are those for my new residue. For next step I get more
> constraint deviation.
> Now, is it possible that this is because of wrong parameters? Or maybe I
> should minimize my system further?
> Here are all the files:
When sharing files, please only post what is actually necessary to reproduce the
problem - a self-contained force field directory, coordinates, topology, .mdp,
and index file if needed. A dump of dozens of files with no context gets
burdensome to go through.
Your minimized geometry is clearly junk. Just visualize the structure and you
will see that your mCherry residue is completely distorted. The very large
(10^4) force after EM should have been the first clue that something is very wrong.
The problems almost certainly stem from the manipulations you've made to the
angles and dihedrals. I don't understand why you've commented some of them out.
For instance, the first angle that you've removed is atoms 977-978-992, which
clearly should have an angle interaction because 977-978 and 978-992 are bonded.
Simply removing "inconvenient" interactions (i.e. lacking parameters or
whatever) leads to a total meltdown of the model.
Justin A. Lemkul, Ph.D.
Ruth L. Kirschstein NRSA Postdoctoral Fellow
Department of Pharmaceutical Sciences
School of Pharmacy
Health Sciences Facility II, Room 601
University of Maryland, Baltimore
20 Penn St.
Baltimore, MD 21201
jalemkul at outerbanks.umaryland.edu | (410) 706-7441
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