[gmx-users] Invalid Order for Directive Defaults Error Due to Force Field Mixing

[Amir Zeb]

Hi Dr. Justin,

I'm wondering that you have mentioned CHARMm27 is not a valid identifier of
protein forcefield, but we have so many articles already published while
using CHARMm27 ff. Can you please let us know how to trace this
unsuitability of CHARMm27 especially for protein-ligand simulation?

Thanks

-Amir

On Thu, Mar 2, 2017 at 2:10 PM, Justin Lemkul <jalemkul at vt.edu> wrote:

>
>
> On 3/2/17 2:16 PM, Sanim Rahman wrote:
>
>> Hi all,
>>
>> I am attempting to run a membrane protein simulation where I am describing
>> my protein and solvent in terms of CHARMM27 and my lipids in CHARMM36.
>> When
>> I use the grompp command, I get the following error:
>>
>> Fatal error:
>> Syntax error - File forcefield.itp, line 9
>> Last line read:
>> '[ defaults ]'
>> Invalid order for directive defaults
>>
>> To create my topology file, I took my protein.top and at the bottom
>> included my lipid.itp and solvent.itp. The error is referencing to my
>> charmm36 force field file. I was unsure what to do so I just removed the
>> line with [ defaults ] on it and tried running it again. This time I
>> received this error:
>>
>> Fatal error:
>> Syntax error - File ffnonbonded.itp, line 5
>> Last line read:
>> '[ atomtypes ]'
>> Invalid order for directive atomtypes
>>
>> Is the source of the error from how my topology files are processing the
>> force field files since I am using both CHARMM27 and CHARMM36? I read a
>> previous thread that you can't have two [ default ] lines which make sense
>> but I am unsure of what is the proper protocol to get around this to
>> include both force fields. Any help will be deeply appreciated!
>>
>>
> I mentioned this last week in another thread, but I'll say it again:
> "CHARMM27" is not a valid identifier for a protein force field.  What
> you're trying to use is CHARMM22/CMAP.
>
> The bigger question is why you want to use this combination?  It may not
> be practical or possible to do so in GROMACS.  You'll likely have to hack
> out the bonded and nonbonded parameters that relate to proteins and marry
> them together with the lipid-only portions of CHARMM36.
>
> -Justin
>
> Thank You,
>>
>> *Sanim Rahman*
>> B.S. Chemical Engineering, 2019
>> Resident Assistant, Castor Hall Engineering Living Learning Community
>> 2016-2017
>> Co-Founder and Co-President of the Undergraduate Research Society
>> Undergraduate Researcher, Global Center for Hearing and Speech Research
>>
>>
> --
> ==================================================
>
> Justin A. Lemkul, Ph.D.
> Ruth L. Kirschstein NRSA Postdoctoral Fellow
>
> Department of Pharmaceutical Sciences
> School of Pharmacy
> Health Sciences Facility II, Room 629
> University of Maryland, Baltimore
> 20 Penn St.
> Baltimore, MD 21201
>
> jalemkul at outerbanks.umaryland.edu | (410) 706-7441
> http://mackerell.umaryland.edu/~jalemkul
>
> ==================================================
>
> --
> Gromacs Users mailing list
>
> * Please search the archive at http://www.gromacs.org/Support
> /Mailing_Lists/GMX-Users_List before posting!
>
> * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists
>
> * For (un)subscribe requests visit
> https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or
> send a mail to gmx-users-request at gromacs.org.
>