[gmx-users] grompp error:Invalid order for directive defaults

David van der Spoel spoel at xray.bmc.uu.se
Mon Jun 12 09:35:19 CEST 2006

Dongsheng Zhang wrote:
> Dear GMX users,
> I'd like to study the interaction between carbon nanotube and a polymer
> chain. I have made cnt.itp for the nanotube and poly.itp. Both itp files
> contains force field parameters (such as [ defaults ], [ atomtypes],
> [ bondtypes ]), in this way, I don't need to include any force field in
> my topology file (but it will include *.itp) and it is much easier to
> modify the parameters. For use nanotube or polymer alone as my system, I
> can use grompp to process .gro, .itp, .top to get .tpr file. If I use
> nanotube and polymer together as my system, grompp give me the following
> error message:
> Invalid order for directive defaults, file ""poly.itp"", line 16 

divide your itp files into two, force field and molecule description

then in your .top file you include all four. chapter 5 in the manual

> line 16 is [ defaults ], so I am thinking maybe I can't have
> [ defaults ] in each of two itp files. If I delete [ defaults ] in the
> second itp file. It will complain [ atomtypes] in the second itp file.
> It seems I can't put force field parameters in two itp files which will
> be included in one topology file. Could anyone tell me if my guessing is
> correct? If so, why does gromacs prevent it? 
> Thank you in advance! If you need more information, I will be more than
> happy to provide it.
> Best wishes!
> Dongsheng
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David van der Spoel, PhD, Assoc. 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://folding.bmc.uu.se

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