[AMBER] Problem with topology file generation

From: Tanmoy Paul via AMBER <amber.ambermd.org>
Date: Fri, 4 Nov 2022 23:19:16 -0400

Dear Amber users,
                                I am Tanmoy from Georgia State University.
I am trying to generate topology and inpcrd files for a system that
contains around 400,000 atoms. Upon solvating, the atom number becomes
around 5,000,000. I used tleap to generate topology and inpcrd files. The
leap.log file did not have any error messages. But while loading them to
VMD, I am getting the following error:

*PARM7: error reading bond number 4015670*

Initially, we thought that it was an issue of visualization. But while
trying to run minimization in NAMD we again encountered the same error. We
were able to generate topology and inpcrd files without the solvent and
ions successfully. It was loaded to vmd without any errors or strange
connections. I checked the prmtop to the best of my ability and found a
strange thing. Under the %FLAG BONDS_INC_HYDROGEN, I can see atom numbers
that are larger than the total number of atoms I have (5530618).

16591827 1161659183316591830 1171659183916591836 11616591842
16591836

I do not know how this is even possible. Can anyone please help?

Here is the script we used :

source leaprc.protein.ff14SB
source leaprc.DNA.bsc1
source leaprc.water.tip3p
loadamberparams /usr/local/amber16/dat/leap/parm/frcmod.ionsjc_tip3p

loadamberprep mg.prep
loadamberparams mg.frcmod

loadoff FeS-nCYS.lib
loadoff CYF.lib
loadamberparams FeS.frcmod

mol = loadpdb model.pdb
desc mol.CYF
desc mol.SF4
bond mol.116.SG mol.761.FE1 #first CYF
bond mol.134.SG mol.761.FE3
bond mol.155.SG mol.761.FE2
bond mol.190.SG mol.761.FE4
bond mol.761.FE1 mol.761.S2
bond mol.761.FE1 mol.761.S3
bond mol.761.FE1 mol.761.S4
bond mol.761.FE2 mol.761.S1
bond mol.761.FE2 mol.761.S3
bond mol.761.FE2 mol.761.S4
bond mol.761.FE3 mol.761.S1
bond mol.761.FE3 mol.761.S2
bond mol.761.FE3 mol.761.S4
bond mol.761.FE4 mol.761.S1
bond mol.761.FE4 mol.761.S2
bond mol.761.FE4 mol.761.S3

solvatebox mol TIP3PBOX 12.0
charge mol
addIonsRand mol Na+ 5660 Cl- 5406
check mol
saveamberparm mol model.prmtop model.inpcrd
quit
-- 
With regards,
Tanmoy
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Received on Fri Nov 04 2022 - 20:30:02 PDT
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