VMD-L Mailing List

From: Gumbart, JC (gumbart_at_physics.gatech.edu)
Date: Fri Oct 13 2023 - 21:49:24 CDT

Hi Joel,

You could just manually add a dummy improper with a force constant of zero for now. You can then optimize the improper after getting the dihedrals.

Best,
JC

On Oct 13, 2023, at 7:52 AM, Joel Subach <mjsubach_at_alumni.ncsu.edu> wrote:

Hello VMD Community, towards the above topic:

Via the ffTK Opt Torsions Tab to optimize dihedral parameters (Tutorial 6.2
link: https://www.ks.uiuc.edu/Training/Tutorials/science/ffTK/fftk-tutorial.pdf).

I had clicked Run Optimization after inputting:

all of the proper files i.e. psf, pdb, par for the input section

my 4-output.out resulting files generated via ORCA for the QM Target Data Section

and my atom types for my two-dihedral angles for the Dihedral Parameter Settings

the below error states:
FATAL ERROR: UNABLE TO FIND IMPROPER PARAMETERS FOR CG2O2 CG2R51 OG2D1 OG311 (ATOMS 17 7 37 36)
[Partition 0][Node 0] End of program
FATAL ERROR: UNABLE TO FIND IMPROPER PARAMETERS FOR CG2O2 CG2R51 OG2D1 OG311 (ATOMS 17 7 37 36)

(See complete Application_Error.log file attached and note within it the: Info: 0 IMPROPER
may have been generated via ffTK?)

Below is a paste of the impropers from my generated .par file:

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
!

* Note i skipped to Scan Torsions since that was all I needed amended i.e. I skipped
Opt. Charges etc. tabs if this would amend the Improper Values, this may make no difference I believe it should not.

For my Opt Torsions `Dihedral Parameter Settings´ i used the Default Values for Force Constant, Periodicity, Phase Shift Lock Phase (0, 1, 0, no respectively).

Please let me know how this Fatal Error could be amended to successfully generate the
Run Optimization? Thanks if you know:), Joel 🚀



<Application_Error.log>