[gmx-users] Fatal error: No atoms found in .rtp file in residue pairs

Justin A. Lemkul jalemkul at vt.edu
Sat May 12 20:06:11 CEST 2012

On 5/12/12 2:00 PM, Shima Arasteh wrote:
> The total charge is zero in real but what I got through swissparam is as below:
> [ atoms ]
> ; nr type resnr resid atom cgnr charge mass
> 1 C=O 1 LIG C 1 0.4500 12.0110
> 2 O=C 1 LIG O 2 -0.5700 15.9994
> 3 HCMM 1 LIG H1 3 0.0600 1.0079
> 4 HCMM 1 LIG H2 4 0.0600 1.0079
> So I entered as I showed you.

What you parameterized was formaldehyde, not a formyl adduct group.  I believe I 
said before to make sure you were deriving parameters appropriately, which it 
appears you are not.

> In addition how can I add the proton on it? Editing the C to CT1 is right? or I
> have to add any charge here?

I don't understand what you're asking here.

The .rtp entry specifies the necessary atoms.  In your case, for a formyl group, 
you need 3 atoms - C, H, and O.  I suspect that this addition will change the 
amino acid residue to which it is attached, in which case you are better off 
deriving a completely new amino acid residue, or at least verifying that your 
new addition does not affect the charges of the existing amino acid (unlikely). 
  I recommended this before; please make sure to heed all available advice 
before plowing ahead and doing something that doesn't make sense.  It wastes 
your time and the that of others who are seeking to help you.

> Formyl is connected to valine in the peptide sequence in this .pdb file. Now,
> what about adding this line ?:
> [ dihedrals ]
> O C +N CA

This is incorrect.  The CA atom is part of valine, thus it is the next residue 
and must also be prefixed with a + sign, as in the case of N.  Using - (minus) 
indicates the previous residue, + the next, and no sign is the present residue. 
  The correct line is:

O  C  +N  +CA



Justin A. Lemkul, Ph.D.
Department of Biochemistry
Virginia Tech
Blacksburg, VA
jalemkul[at]vt.edu | (540) 231-9080


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