Incorrect sign arg for dihedral coefficients

LAMMPS LAMMPS Mailing List Mirror
1

Dear lammps users,

I want to perform an energy minimization on my structure with UFF force field. I have prepared my data file in which the dihedral section is as follow:

Dihedral Coeffs # harmonic

1 0.000000 0 0 # O_R-Cr6+3-O_R-C_R
2 0.000000 0 0 # O_2-Cr6+3-O_R-C_R
3 0.000000 0 0 # O_R-Cr6+3-O_2-Cr6+3
4 2.245703 -1 2 # Cr6+3-O_R-C_R-O_R
5 0.000000 0 0 # Cr6+3-O_R-C_R-C_R **
6 0.000000 0 0 # F_-Cr6+3-O_R-C_R
7 0.000000 0 0 # H_-C_R-C_R-H_**
8 1.497136 -1 2 # C_R-C_R-C_R-H_
9 0.000000 0 0 # C_R-C_R-C_R-C_R **
10 0.555556 -1 2 # O_R-C_R-C_R-C_R
11 0.000000 0 0 # F_-Cr6+3-O_2-Cr6+3

I could not find UFF parameters for the lines specified by stars.

when I run my code, I face this error:

ERROR: Incorrect sign arg for dihedral coefficients (…/dihedral_harmonic.cpp:290).

I changed the sign of 1 in dihedrals but it does not work. I don not know what the problem is. Any help will be appreciated.

Regards,
Mina

2

Dear lammps users,

I want to perform an energy minimization on my structure with UFF force field. I have prepared my data file in which the dihedral section is as follow:

  Dihedral Coeffs # harmonic

  1 0.000000 0 0 # O_R-Cr6+3-O_R-C_R
  2 0.000000 0 0 # O_2-Cr6+3-O_R-C_R
  3 0.000000 0 0 # O_R-Cr6+3-O_2-Cr6+3
  4 2.245703 -1 2 # Cr6+3-O_R-C_R-O_R
  5 0.000000 0 0 # Cr6+3-O_R-C_R-C_R **
  6 0.000000 0 0 # F_-Cr6+3-O_R-C_R
  7 0.000000 0 0 # H_-C_R-C_R-H_**
  8 1.497136 -1 2 # C_R-C_R-C_R-H_
  9 0.000000 0 0 # C_R-C_R-C_R-C_R **
10 0.555556 -1 2 # O_R-C_R-C_R-C_R
11 0.000000 0 0 # F_-Cr6+3-O_2-Cr6+3

I could not find UFF parameters for the lines specified by stars.

which is really, really bad. you cannot expect reasonable results,
when part of your interactions is missing.

when I run my code, I face this error:

ERROR: Incorrect sign arg for dihedral coefficients (../dihedral_harmonic.cpp:290).

I changed the sign of 1 in dihedrals but it does not work. I don not know what the problem is. Any help will be appreciated.

please look at the documenation! it clearly says, that the parameter
"d" must be either "1" or "-1".
if you use a recent enough version of LAMMPS it should tell you which
line exactly this refers to.

...and if you look at the formula, you should realize, that a value of
0 for "d" makes no sense whatsoever in the first place.
all of these terms have a force constant of zero, so it doesn't really
matter what kind of values you enter for those those are contributing
not forces.

axel.