[CP2K-user] INCORRECT TORSION ENERGY WHEN USING AMBER PARAMETERS

[Ajay Muralidharan]

Hello all,
I noticed that torsions evaluated by CP2K when using AMBER parameters are 
exactly half of the correct answer. Here is the description below.

I do single point energies of a small dipeptide in vacuum using amber 
forcefield. (attached input files)
Gromacs and OPENMM give the same intramolecular energy components.
_____________________________________________
However CP2K does not:
more 1.out | grep -A 2 "FIST energy"

 FIST energy contributions in kcal/mol:

 BOND    =       17.8009  ANGLE   =       34.4220  UBRAD   =        0.0000

 TORSION =       10.0356  IMPTORS =        0.0000  OPBEND  =        0.0000
BOND = 17.8009* 4.184 = 74.478 kJ/mol
ANGLE = 34.4220 * 4.184 = 144.021 kJ/mol
TORSION = 10.0356 * 4.184 = *41.988 kJ/mol*
_____________________________________________________

GROMACS (after converting amber.prmtop -> Gromacs topology)
BOND = 74.478 kJ/mol
ANGLE = 144.021 kJ/mol
TOTAL TORSIONS =  80.691(proper) + 3.2858 (improper) = *83.3549 kJ/mol *
 *(Exactly double as that from CP2K!) *
TOTAL PE = ~251 kJ/mol. (This matches exactly with OPENMM when using 
amber.prmtop )
So Gromacs and openmm results agree with each other. 
______________________________________________________

Then saw this post: 
*https://groups.google.com/forum/#!searchin/cp2k/amber$20torsion%7Csort:date/cp2k/PeMpumD2oXU/1uWBed2IfhkJ 
<https://groups.google.com/forum/#!searchin/cp2k/amber$20torsion%7Csort:date/cp2k/PeMpumD2oXU/1uWBed2IfhkJ>*

mpirun -n 1 cp2k.popt --version

 CP2K version 6.1

 SVN source code revision svn:18464

 cp2kflags: libint fftw3 libxc parallel mpi3 scalapack xsmm 
libderiv_max_am1=5 libint_max_am=6 plumed2 mkl

*(Seems like TORSIONS is still broken in svn:18464)*

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20200123/3d96fe8b/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 1.inp
Type: chemical/x-gamess-input
Size: 1013 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20200123/3d96fe8b/attachment.inp>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 1.out
Type: application/octet-stream
Size: 110049 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20200123/3d96fe8b/attachment.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: amber.prmtop
Type: application/octet-stream
Size: 22238 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20200123/3d96fe8b/attachment-0001.obj>