From: Zeinab Emami (zemami_at_ku.edu.tr)
Date: Mon Oct 20 2014 - 12:44:19 CDT

Dear Christopher Mayne,

I read your answer:

I should specify that in the screencast tutorials we did not include the
standard CGenFF parameter file as the "associated parameter file" because
we wanted to treat pyrrolidine as if it were completely unknown (it is
included in the standard CGenFF files). When building the initialized
parameter file, ffTK first determines all of the parameters needed to
describe the molecule (using the information in the PSF), and then
crosschecks these required parameters against any parameter sets listed as
"associated parameter files." ffTK will only write out the parameters that
it does not find. In this case, if you included the CGenFF parameter file,
ffTK will find all of the parameters it is looking for and will generate an
empty parameter file.

The matter is that, we are at the phase pf learning. Therefore, we want to
know how ffTK works for a completely unknown molecule. In that case, we
expect to get an initial parameter file with the initial values [for bonds,
angel..] all set to zero. But the initial parameter file we get from the
first step in ffTK is oddly void of any atom, and it contains only
comments. The file content is pasted below.

Best Regards,
Zeinab

!=============================================================
!
! Parameter file generated by the Force Field ToolKit (ffTK)
!
! For additional information, see:
! http://www.ks.uiuc.edu/Research/vmd/plugins/fftk
! http://www.ks.uiuc.edu/Research/fftk
!
! Authors:
! Christopher G. Mayne
! Beckman Institute for Advanced Science and Technology
! University of Illinois, Urbana-Champaign
! http://www.ks.uiuc.edu/~mayne
! mayne_at_ks.uiuc.edu
!
! James C. Gumbart
! Georgia Institute of Technology
! http://simbac.gatech.edu
! gumbart_physics.gatech.edu
!
! If you use parameters developed using ffTK, please cite:
! C.G. Mayne, J. Saam, K. Schulten, E. Tajkhorshid, J.C. Gumbart. J.
Comput. Chem. 2013, 34, 2757-2770.
!
!=============================================================

BONDS
!V(bond) = Kb(b - b0)**2
!
!Kb: kcal/mole/A**2
!b0: A
!
!atom type Kb b0
!

ANGLES
!
!V(angle) = Ktheta(Theta - Theta0)**2
!
!V(Urey-Bradley) = Kub(S - S0)**2
!
!Ktheta: kcal/mole/rad**2
!Theta0: degrees
!Kub: kcal/mole/A**2 (Urey-Bradley)
!S0: A
!
!atom types Ktheta Theta0 Kub S0
!
!

DIHEDRALS
!
!V(dihedral) = Kchi(1 + cos(n(chi) - delta))
!
!Kchi: kcal/mole
!n: multiplicity
!delta: degrees
!
!atom types Kchi n delta
!

IMPROPER
!
!V(improper) = Kpsi(psi - psi0)**2
!
!Kpsi: kcal/mole/rad**2
!psi0: degrees
!note that the second column of numbers (0) is ignored
!
!atom types Kpsi psi0
!

NONBONDED nbxmod 5 atom cdiel shift vatom vdistance vswitch -
cutnb 14.0 ctofnb 12.0 ctonnb 10.0 eps 1.0 e14fac 1.0 wmin 1.5
!
!V(Lennard-Jones) = Eps,i,j[(Rmin,i,j/ri,j)**12 - 2(Rmin,i,j/ri,j)**6]
!
!epsilon: kcal/mole, Eps,i,j = sqrt(eps,i * eps,j)
!Rmin/2: A, Rmin,i,j = Rmin/2,i + Rmin/2,j
!
!atom ignored epsilon Rmin/2 ignored eps,1-4 Rmin/2,1-4
!

END

On Mon, Oct 20, 2014 at 7:34 PM, Zeinab Emami <zemami_at_ku.edu.tr> wrote:

>
> Hello,
>
> I am trying to test production of parameter files following the
> molefacture
> tutorial and these video series about ffTK:
>
> http://www.ks.uiuc.edu/Research/vmd/minitutorials/fftk/
>
>
> http://www.ks.uiuc.edu/Training/Tutorials/vmd-molefacture/tutorial-Molefacture.pdf
>
>
> I loaded my molecule to VMD, then invoked molefacture, edited the atom
> names, charges and type. then using "file/ write psf and pdb file"
> produced
> the psf and pdb files I need for the ffTK procedure. [VIDEO 1]
>
> Then, I loaded the psf and pdb file in fftk/BuildPar/Identify Missing
> Parameters and produced the parameter file, as it is described in the
> video
> 2.
>
> The proper parameter file, as shown in video 2, should contain the atoms
> and the values for bonds, angles and so on; and the values are set to
> zero.
> Although, in the parameter file I got, there is no value, just comments;
> it
> seems to me that VMD cannot read the pdb and psf files produced by
> molefacture.
>
> I hope these info are enough.
>
> Best Regards,
> ZE
>
>
>