ERROR: " Expected floating point parameter instead of '−0.2106' in input script or data file"

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1

Greetings,

I have looked at a similar error posted on the mailing list archives, however the solution doesn’t seem applicable in my case. I am equilibrating a box of about 1000 beads in the NPT ensemble and the styles and parameters have been chosen based on polymerization I plan to do post equilibration.

However, this error presents itself when reading the Dihedral Coeffs (fourier) part of the data file. I am attaching the files for your references as well as listing the script below:

-------------------------------LAMMPS File------------------------

units real
dimension 3
boundary p p p
atom_style full
pair_style lj/cut 15.0
bond_style class2
angle_style class2
dihedral_style fourier

neighbor 5.0 bin
neigh_modify delay 10

read_data pack_M.lmp

angle_coeff 1 99.8 8.25 0.320848 0.294303 #Class2 style = TEAM-MS style for #Ea term
angle_coeff 1 bb 0.0 0.0 0.0 #No BB term in force field TEAM-MS
angle_coeff 1 ba 0.0 0.0 0.0 0.0 #No BA term in force field TEAM-MS angle_coeff 2 99.8 10.03 0.24716 0.25374
angle_coeff 2 bb 0.0 0.0 0.0
angle_coeff 2 ba 0.0 0.0 0.0 0.0

compute 1 all temp/com
compute 2 all com
compute 3 all pressure 1
compute 4 all rdf 50 * * cutoff 25.0

minimize 1.0e-4 1.0e-6 1000 100000

fix 1 all langevin 300.0 300.0 150 12345

thermo 100
thermo_style custom step temp press etotal epair c_2 vol density
thermo_modify norm yes temp 1

run 5000

unfix 1

fix fxNPT all npt temp 300.0 300.0 500.0 iso 1.0 1.0 500.0

thermo 100
thermo_style custom step temp press etotal epair c_2 vol density
thermo_modify norm yes temp 1

run 100000

write_data system_npt_relax.data

----------------------Data File------------------------

1015 atoms
0 bonds
0 angles
0 dihedrals
0 impropers
2 atom types
3 bond types
2 angle types
2 dihedral types
0 improper types
2 extra bond per atom
9 extra angle per atom
16 extra dihedral per atom
-2.500000 113.500000 xlo xhi
-2.500000 113.500000 ylo yhi
-2.500000 113.500000 zlo zhi

Masses

1 74.15294 # M
2 81.18766 #E

Atoms # full

##Not including coordinates as 1015 atoms will take too much space##

Pair Coeffs

1 1 0.533811 5.653 #14.1325
2 2 0.323278 5.613 #14.0325

Bond Coeffs #class2

1 3.500 30.5 -0.002151 0.00251
2 3.553 38.5 -0.001351 0.001584
3 3.553 38.5 -0.001351 0.001584

#Angle Coeffs #class2

Dihedral Coeffs #fourier

1 3 −0.2106 1 0.0 0.1689 2 180.0 0.1217 3 0.0
2 3 −0.2634 1 0.0 0.1872 2 180.0 0.117 3 0.0

Thanking you in advance for your help.

Your sincerely,

pack_M.lmp (54.4 KB)

NPT_min.in.lmp (2.89 KB)

2

You have non-ascii characters in your data file in the DihedralCoeffs section.

This often happens when carelessly doing a cut-n-paste from a webpage or a PDF file.
those tend to replace some standard characters with similarly looking UTF-8 characters.

LAMMPS detects such incorrect usage as the system library atof() would convert such a string like -0.2106 unexpectedly to a value of 0.0, which is clearly not what you want.

axel.